228 F.3d 816 (7th Cir. 2000)
United States of America, Plaintiff-Appellee,v.Lucky Irorere, Defendant-Appellant.
No. 99-3671
In the  United States Court of Appeals  For the Seventh Circuit
Argued May 19, 2000Decided September 26, 2000

Appeal from the United States District Court for the Northern District of Illinois, Eastern Division.  No. 98 CR 245-2--Harry D. Leinenweber, Judge.[Copyrighted Material Omitted][Copyrighted Material Omitted][Copyrighted Material Omitted]
Before Flaum, Chief Judge, and Manion and Williams,  Circuit Judges.
Flaum, Chief Judge.


1
Defendant Lucky Irorere  appeals his conviction of conspiring to import  heroin in violation of 21 U.S.C. sec. 952(a), 21  U.S.C. sec. 963, and 18 U.S.C. sec. 2, as well as  his conviction of importing heroin in violation  of 21 U.S.C. sec. 952(a) and 18 U.S.C. sec. 2.  The defendant argues that the evidence presented  at trial was insufficient for a jury to convict  him of conspiring to import heroin and importing  heroin and that the district court erred in  refusing to explicitly instruct the jury that the  defendant had to have knowledge of the foreign  origins of the heroin in order to be convicted of  both charges. The defendant also contends that  the district court erred in refusing to appoint  a lawyer to represent him at sentencing and in  denying his motion for a new trial based on  statements made by his alleged co-conspirators  during their plea colloquies. In addition, the  defendant claims that the indictment issued  against him was void because it allegedly lacked  the signatures of the grand jury foreperson and  an attorney for the government. For the reasons  stated herein, we affirm the district court.

I.  Background

2
The charges of which the defendant was  convicted stem from an extensive investigation of  drug trafficking between Thailand and the United  States. As part of this operation, the Drug  Enforcement Administration ("DEA") placed Mark  Lasyone, a cooperating source, in Thailand.  Lasyone was eventually introduced to several  members of a purported drug trafficking  organization, including Haas David Kalusha, also  known as Nicholas Onaro, and Onaro's girlfriend,  Thiamchan Chiawan.


3
As part of the drug trafficking investigation  in which Lasyone was participating, DEA agents  Anthony Thomas and Jeff Johnson posed as  Lasyone's contacts in the United States. In  addition, the DEA office in Chicago obtained an  undercover fax number and two undercover postal  addresses to be used as a point of receipt for  heroin shipped to the United States. Once these  undercover addresses were established, Lasyone  informed Onaro that he could arrange locations in  the United States that could accept delivery of  heroin and subsequently notified Onaro of the  existence of the two undercover postal addresses.


4
Following Onaro's receipt of the undercover  postal addresses, two separate shipments of  heroin were sent to the United States. On January  22, 1998, a package containing 289.9 grams of  heroin arrived at one of the undercover addresses  following the receipt of a fax from "David," an  alias of Onaro's, indicating that the "samples"  had been shipped. A second package containing  310.7 grams of heroin arrived at one of the  undercover postal addresses on March 24, 1998.  The defendant contacted Agent Thomas shortly  after the arrival of both of these shipments.


5
On March 30, 1998, Chiawan traveled to the  United States where she met Agent Thomas, whom  she believed to be Lasyone's son-in-law. Agent  Thomas and Chiawan planned to deliver the heroin,  obtain payment for it, and return to a nearby  hotel to meet Lasyone. On the same day that  Chiawan arrived in the United States, the  defendant contacted Lasyone to inform him that  everything had arrived. Although the defendant  arranged a meeting between himself, Agent Thomas,  and Chiawan for March 31, 1998, that meeting was  rescheduled for the following day at the request  of the defendant.


6
After the defendant cancelled the March 31,  1998 meeting, Lasyone became dissatisfied with  the defendant's handling of the drug transaction.  On April 1, 1998, Lasyone telephoned Onaro to  complain about the defendant's conduct. Shortly  after this call, Agent Thomas and Agent Johnson  arrived at Chiawan's hotel to meet with the  defendant. The agents met the defendant in the  hotel lobby and then proceeded to Chiawan's room  where the defendant and Agent Thomas discussed  payment arrangements. When Agent Thomas expressed  concern over the defendant's failure to produce  any money in payment for the heroin shipment, the  defendant responded that he had a long-standing  relationship with Onaro and that Agent Thomas  should call Onaro to discuss it with him.


7
In an attempt to break the impasse over the  method of payment for the drugs, Agent Thomas  called Lasyone and arranged for Lasyone to  telephone Onaro. When Agent Thomas informed the  defendant that Lasyone was going to contact  Onaro, the defendant stated that he had been  surprised by Agent Thomas's request for immediate  payment and that he would be prepared next time.  The defendant also said that he had talked to  Lasyone at least twice and that no one had ever  mentioned money.


8
After speaking with Agent Thomas, Lasyone  telephoned Onaro in Thailand and complained that  the defendant had not brought any money with him  to the exchange. Although Onaro agreed that it  was Agent Thomas's decision as to whether the  transaction would proceed, Agent Thomas  eventually relented and decided to go forward  without payment in advance. Agent Thomas then  sent Agent Johnson to retrieve a package that was  purportedly filled with heroin. When Agent  Johnson returned, the package was shown to the  defendant and placed in the defendant's duffel  bag. The defendant was arrested as soon as he  took possession of the heroin.


9
Following his arrest, the defendant waived his  Miranda rights and gave a post-arrest statement  to the government. In that statement, the  defendant said that he was first contacted by an  associate who gave him Onaro's phone number and  who told him that David in Thailand was trying to  contact him. The defendant also described various  aspects of the heroin shipment from Thailand to  the United States and admitted that he traveled  to Chicago to pick up the drugs that Onaro sent  from Thailand.


10
On October 12, 1999, the defendant was  convicted of conspiring to import heroin in  violation of 21 U.S.C. sec. 952(a), 21 U.S.C.  sec. 963, and 18 U.S.C. sec. 2, as well as  importing heroin in violation of 21 U.S.C. sec.  952(a) and 18 U.S.C. sec. 2. Based on these  convictions, the defendant was sentenced to one  hundred months in prison. The defendant now  appeals, alleging various errors on the part of  the district court during both the guilt and  sentencing phases of trial.

II.  Analysis
A.  Sufficiency of the Evidence

11
At trial, the defendant made a motion for a  judgment of acquittal, arguing that the  government did not present sufficient evidence to  prove beyond a reasonable doubt that he conspired  to import the heroin in question or that he  imported it. "Challenging the sufficiency of the  evidence is an uphill battle and the defendant  bears a heavy burden." United States v. Wallace,  212 F.3d 1000, 1003 (7th Cir. 2000). In reviewing  the defendant's sufficiency of the evidence  claim, "[w]e consider the evidence in the light  most favorable to the government, drawing all  reasonable inferences in its favor." United  States v. Frazier, 213 F.3d 409, 416 (7th Cir.  2000). As an appellate court, we will not reweigh  the evidence presented or second-guess the jury's  credibility determinations. See United States v.  Alcantar, 83 F.3d 185, 189 (7th Cir. 1996)  ("Questions of witness credibility are reserved  for the jury, and its assessment will not be  second-guessed by an appellate panel."); United  States v. Hubbard, 22 F.3d 1410, 1415 (7th Cir.  1994). "'Only when the record contains no  evidence, regardless of how it is weighed, from  which the jury could find guilt beyond a  reasonable doubt, may an appellate court overturn  the verdict.'" United States v. Lundy, 809 F.2d  392, 396 (7th Cir. 1987); see also Jackson v.  Virginia, 443 U.S. 307, 319 (1979) (stating that  the test for the sufficiency of the evidence is  "whether . . . any rational trier of fact could  have found the essential elements of the crime  beyond a reasonable doubt") (emphasis in  original).


12
Initially, we want to emphasize that the  evidence presented at trial was clearly  sufficient to establish that the defendant's  participation in Onaro's drug trafficking  activities was more substantial than the kind of  buyer-seller relationship that this Court has  rejected as the basis for a conspiracy charge.  See United States v. Lechuga, 994 F.2d 346, 349  (7th Cir. 1993) (en banc) (holding that evidence  of a mere buyer-seller relationship does not  support a conspiracy charge). As early as  February 16, 1998, more than a month before the  heroin at issue was mailed to the United States,  the defendant mentioned his relationship with  Onaro to Agent Thomas and alluded to the proposed  heroin deal. The defendant admitted of his  ongoing relationship with Onaro during subsequent  conversations with DEA agents when he stated that  he knew "David" and that he had been working with  him, and Onaro's willingness to allow the  defendant to sell the drugs on consignment  reflects the existence of a prior and ongoing  relationship of trust, a fact which can be  evidence of a conspiracy, see United States v.  Ferguson, 35 F.3d 327, 331 (7th Cir. 1994)  ("[E]vidence of providing [drugs] 'up front' may  establish the existence of a conspiracy . . .  because it indicates cooperation and trust rather  than an arm's length retail-type sale."). This  evidence is sufficient for a rational jury to  find that the defendant both agreed to  participate in the relevant heroin transaction  and assisted in that transaction, and we  therefore reject the defendant's sufficiency of  the evidence claim insofar as he contends that he  participated in the transaction only as a buyer  of the heroin once it reached the United States.


13
The fact that the government established the  defendant's participation in the heroin  transaction as more than a buyer is significant,  but the defendant does not focus on that aspect  of the crimes of conviction. Rather, the  defendant's sufficiency of the evidence challenge  centers on the state of mind element of the crime  of importation. As the defendant correctly points  out, both the conspiracy charge and the  government's aiding and abetting theory of  liability for importation require a showing of  specific intent. See United States v. Andujar, 49  F.3d 16, 20 (1st Cir. 1995) (stating that a  conspiracy conviction requires both "'intent to  agree and intent to commit the substantive  offense'") (quoting United States v. Garcia, 983  F.2d 1160, 1165 (1st Cir. 1993)); United States  v. Labat, 905 F.2d 18, 23 (2d Cir. 1990) (noting  that aiding and abetting requires specific intent  to bring about the commission of a crime). In  order for the jury to find the defendant guilty  of importation, the government must establish  that the defendant knew that the drugs in  question originated outside the United States.  See Seventh Circuit Federal Jury Instructions: Criminal 392-93 cmt. (1999) ("Although the  statute itself contains no intent requirement,  the cases also make clear that the statute is a  specific intent statute which requires the  government to prove both that the defendant  knowingly imported the substance in question and  that the defendant knew the substance was a  controlled substance.") (citing cases). According  to the defendant, it is his knowledge of the  imported nature of the drugs that the government  failed to establish at trial.


14
It is clear that the government has the burden  of demonstrating beyond a reasonable doubt that  the defendant knew the drugs were imported.  However, the government need not establish the  elements of the conspiracy and importation  charges through direct evidence in order to  satisfy its burden of proof. See United States v.  Pagan, 196 F.3d 884, 889 (7th Cir. 1999)  ("Conspiracy . . . may be proved entirely by  circumstantial evidence."); United States v.  Coleman, 179 F.3d 1056, 1061 (7th Cir. 1999)  (stating that an individual's guilt under an  aiding and abetting theory "'may be established  by circumstantial evidence'") (quoting United  States v. McKneely, 69 F.3d 1067, 1072 (10th Cir.  1995)). Rather, the government may establish the  existence of a conspiracy, and the defendant's  involvement in importing heroin, "through  circumstantial evidence and any reasonable  inferences drawn therefrom involving the  defendant['s] relationship, overt acts, and  overall conduct." United States v. Castillo, 148  F.3d 770, 774 (7th Cir. 1998).


15
Contrary to the defendant's assertions regarding  the sufficiency of the evidence as to his  knowledge of the imported nature of the drugs,  there is circumstantial evidence from which a  rational jury could conclude that the defendant  knew that the heroin in question originated in  Thailand. The defendant made several calls to  Agent Thomas to discuss various aspects of the  heroin transaction, and the content of these  calls indicates an awareness of both the details  of Onaro's drug trafficking activities and  knowledge of Onaro's intent to ship drugs from  Thailand to the United States. More  significantly, the defendant referred to  conversations that he had with Onaro while Onaro  was in Thailand and the defendant himself  admitted that when Onaro first contacted him he  knew that Onaro was mailing drugs to the United  States from Thailand. The defendant further knew  that most of the principals in this heroin  transaction lived and operated out of Thailand.  Against this factual backdrop, we cannot conclude  that the evidence presented at trial was  insufficient to establish that the defendant knew  that the heroin he took possession of in the  United States originated in Thailand. This  evidence, taken together with the testimony and  evidence indicating the defendant's involvement  in the heroin transaction, is sufficient for a  rational trier of fact to conclude that the  defendant conspired to import heroin and imported  heroin.1 Accordingly, we reject the defendant's  sufficiency of the evidence claim.

B.  The Jury Instructions

16
The defendant next contends that the district  court erred in instructing the jury on the  necessary elements of the crimes of conspiracy to  import heroin and importing heroin. As we stated  in connection with the defendant's sufficiency of  the evidence claim, both conspiracy and  importation require a showing of specific intent.  See Andujar, 49 F.3d at 20 (stating that a  conspiracy conviction requires both "'intent to  agree and intent to commit the substantive  offense'") (quoting Garcia, 983 F.2d at 1165);  Seventh Circuit Federal Jury Instructions: Criminal 392-93 cmt. (emphasizing that  importation is a specific intent crime); see also  Labat, 905 F.2d at 23 (noting that aiding and  abetting requires specific intent to bring about  the commission of a crime). According to the  defendant, the instruction given on the  importation offense underlying both of his  charged crimes did not adequately express the  requirement that the jury find that he knew the  drugs he took possession of were imported.


17
The district court gave the following jury  instruction on the importation charge


18
"To  sustain [the charge of importation of controlled  substances] against the defendant in Count 3 of  the indictment, the Government must prove the  following propositions: First, that the defendant  imported heroin into the United States from any  place outside thereof; and, second, that the  defendant knew the substance he possessed was a  controlled substance." Although this instruction  is modeled on the Seventh Circuit's pattern  instruction for a charge under 21 U.S.C. sec.  952(a), see Seventh Circuit Federal Jury  Instructions: Criminal 392, the defendant  requested that the jury be explicitly informed  that in order to convict the defendant of  importation it had to find that the defendant  knew that the heroin in question originated  outside the United States. According to the  defendant, such an instruction was necessary  because his theory of defense was that although  he possessed the heroin once it reached the  United States, he was not aware it had been  shipped from Thailand. If the jury believed this  defense, and had any reasonable doubt as to the  defendant's knowledge of the imported nature of  the drugs, it would have been required to acquit  on both the importation and conspiracy charges.  See id. at 392-93 cmt.


19
Although we believe that the district court's  reliance on our pattern instruction was  understandable, there are circumstances where the  Seventh Circuit pattern instruction on a given  charge will be inadequate. According to the  defendant, the central problem with the jury  instructions in this case is that the defendant's  theory of defense--that he possessed the drugs  once they arrived in the United States but did  not know that they were imported--is not  reflected in the pattern instruction on  importation. See United States v. Douglas, 818  F.2d 1317, 1322 (7th Cir. 1987) (holding that a  model jury instruction can be inadequate in  circumstances where the "case . . . involves a  theory of defense that is not reflected in that  instruction"). We have previously held that  "'[t]he defendant in a criminal case is entitled  to have the jury consider any theory of the  defense which is supported by law and which has  some foundation in the evidence, however tenuous.'"  United States v. Boucher, 796 F.2d 972, 975 (7th  Cir. 1986) (quoting United States v. Grimes, 413  F.2d 1376, 1378 (7th Cir. 1969)). However, a  criminal defendant's entitlement to a theory-of-  defense instruction is limited to circumstances  where: (1) "the defendant proposes a correct  statement of the law;" (2) "the defendant's  theory is supported by the evidence;" (3) "the  defendant's theory of defense is not part of the  charge;" and (4) "the failure to include an  instruction on the defendant's theory of defense  in the jury charge would deny the defendant a  fair trial." Douglas, 818 F.2d at 1320-21.


20
The defendant's burden of demonstrating that he  was entitled to an instruction on his theory of  defense is further complicated by the applicable  standard of review. In circumstances where the  defendant makes a proper objection, we review a  district court's decision regarding the language  of a proposed jury instruction for an abuse of  discretion, see Spiller v. Brady, 169 F.3d 1064,  1066 (7th Cir. 1999), and its decision not to  instruct on a theory of defense de novo, see  United States v. Meyer, 157 F.3d 1067, 1074 (7th  Cir. 1998). At trial, the defendant did contest  the government's proposed instruction and  requested that the district court instruct the  jury that, in order to convict on the conspiracy  and importation charges, it had to determine that  the defendant knew the imported nature of the  heroin. However, "[m]erely submitting  instructions is not sufficient" to preserve an  objection. Douglas, 818 F.2d at 1320. Rather, "a  defendant must object, on the record, to the  judge's refusal to tender the defendant's  instructions, and must clearly state the reasons  for his or her objections." Id. (citing United  States v. Green, 779 F.2d 1313, 1320 n.6 (7th  Cir. 1985)); see also Fed.R. Crim.P. 30. Here,  the defendant's counsel did not object on the  record at the time the district court refused to  give the defendant's proposed instruction, but  rather accepted the district court's  representation that the importation instruction  contained an implicit knowledge requirement and  confirmed that he could argue a lack of knowledge  to the jury. As a consequence of his failure to  specifically object to the district court's  refusal to offer an explicit theory-of-defense  instruction, the defendant has not adequately  preserved his objection to the district court's  instructions and we therefore review the  defendant's challenge under the more deferential  plain error standard. Douglas, 818 F.2d at 1320.


21
As we noted above, there are circumstances  where a pattern instruction will be insufficient  and where a criminal defendant is entitled to an  explicit jury instruction encapsulating his  theory of defense. Id. at 1322. However, as we  also stated, a defendant is only entitled to such  an instruction when his theory of defense is not  already adequately captured by the proffered  instructions. Id. at 1321. The district court  refused to explicitly instruct the jury that the  defendant had to know of the imported nature of  the heroin because the court believed that this  specific intent element was already contained in  the pattern instruction on importation. The  district court's statement to this effect was  apparently accepted by defense counsel, and  nothing in the record indicates that the  defendant was precluded from presenting his  theory of defense to the jury. Although we  believe that the district court might have been  better served by making the disputed mental state  element of importation explicit in the  instruction, the defendant's failure to properly  preserve his objection renders our review  deferential. Absent a more persuasive showing  that the pattern instruction on importation did  not adequately inform the jury of all the  elements of the crime of importation, we cannot  conclude that the district court plainly erred in  rejecting the defendant's proposed instruction in  favor of the pattern instruction.


22
Our conclusion that the defendant has not  demonstrated his entitlement to an explicit jury  instruction on his theory of defense is bolstered  by the defendant's inability to show that any  alleged failure of the district court to give  such an instruction deprived him of a fair trial.  See id. at 1321 (stating that a defendant is only  entitled to a theory-of-defense instruction if  the failure to include such an instruction "would  deny the defendant a fair trial"). The district  court not only delivered an instruction which  both parties accepted on the ground that it  contained an implied specific intent requirement,  but defense counsel was clearly informed that he  could argue to the jury that the defendant did  not know that the drugs originated in a foreign  country. Defense counsel made the most of this  opportunity by focusing important parts of his  cross-examinations, as well as a significant part  of his closing argument, on the defendant's  alleged lack of knowledge that the drugs came  from Thailand. Moreover, while the importation  instruction lacked a specific mental state  requirement, both the indictment, which was read  and provided to the jury, and the aiding and  abetting instruction indicated that the defendant  had to knowingly aid in the importation of drugs.  See Trident Investment Management, Inc. v. Amoco  Oil Co., 194 F.3d 772, 780 (7th Cir. 1999)  (recognizing that "[n]o instructions are perfect,  but the rule is that we will not find reversible  error in jury instructions if, taken as a whole,  they fairly and accurately inform the jury about  the law"). Under these circumstances, we are not  convinced that the failure of the district court  to give an explicit theory-of-defense instruction  prejudiced the defendant. Because we conclude  that the defendant has not demonstrated that the  importation charge given to the jury did not  include his theory of defense, and because the  defendant has not shown that any oversight that  may have occurred in that regard denied him a  fair trial, we cannot overturn the district  court's decision regarding the jury instructions.

C.  The Defendant's Right to Counsel

23
The defendant also argues that the district  court erred in refusing to provide the defendant  a lawyer at his sentencing hearing. It is well-  established that "[t]he Sixth Amendment  guarantees the right to counsel during all  'critical stages of the prosecution'" United  States v. Veras, 51 F.3d 1365, 1369 (7th Cir.  1989) (quoting United States v. Wade, 388 U.S.  218, 238 (1967)), and that this right is  applicable during sentencing hearings, see United  States v. Ayala-Rivera, 954 F.2d 1275, 1279 (7th  Cir. 1992). However, a defendant may waive his  right to counsel through his own contumacious  conduct. See United States v. Fazzini, 871 F.2d  635, 642 (7th Cir. 1989). In this case, the  district court refusedto appoint the defendant  counsel at his sentencing hearing because the  court found that the defendant, through his own  conduct, had already frustrated four attempts by  the district court to provide the defendant with  representation and had thereby waived his right  to counsel. Whether the defendant has waived his  right to counsel is a practical determination  that depends on the particular facts and  circumstances of each case, "including the . . .  conduct of the accused." McQueen v. Blackburn,  755 F.2d 1174, 1177 (5th Cir. 1985). We review  the district court's refusal to appoint counsel  for an abuse of discretion, see McNeil v. Lowney,  831 F.2d 1368, 1371 (7th Cir. 1987), and we will  not reverse the district court's decision "unless  it would result in fundamental unfairness  impinging on due process rights," Maclin v.  Freake, 650 F.2d 885, 886 (7th Cir. 1981).


24
In order to determine whether the defendant did  knowingly and voluntarily waive his Sixth  Amendment right to counsel through his own  conduct, we must review the facts surrounding the  district court's decision not to appoint the  defendant counsel for purposes of his sentencing  hearing. The defendant was originally represented  by a public defender, Luis Galvan, but Galvan  withdrew from this representation because he felt  that he did not have a relationship of trust with  the defendant and because he regarded the  defendant's attitude as abusive and antagonistic.  Michael Falconer was then appointed to represent  the defendant, but the defendant later requested  that Falconer be dismissed as his defense counsel  because of Falconer's allegedly poor performance  and abusive attitude. In response to the  defendant's request for his dismissal, Falconer  informed the district court that the defendant  would not cooperate with him, and stated that the  defendant seemed to feel that he was entitled to  an unlimited number of attorneys. During this  discussion of Falconer's representation, the  defendant first raised the possibility that  Galvan could be reappointed and then decided that  he wanted to represent himself. The district  court advised against proceeding pro se and  ordered Falconer to remain as "shadow counsel."  The district court also strongly encouraged the  defendant to consult Falconer for assistance on  the case.


25
On October 20, 1998, the district court allowed  Falconer to withdraw from his representation of  the defendant and reappointed Galvan. However,  after serving as the defendant's counsel for  approximately three months, Galvan again  requested to withdraw. In support of this  request, Galvan stated that the defendant accused  him of "working in conjunction with the  government to prejudice [the defendant's]  interests" and of lying to him during their  consultations. The district court granted  Galvan's motion to withdraw and appointed Robert  Clarke as counsel for the defendant. Clarke  represented the defendant at trial but, after the  defendant was convicted, the defendant filed a  complaint against Clarke with the Attorney  Registration and Disciplinary Commission. Clarke  then sought to withdraw as the defendant's  counsel and the district court granted Clarke's  motion. Following Clarke's withdrawal from the  case, the district court asked Carl Clavelli to  represent the defendant and delayed the  defendant's sentencing date in order to give  Clavelli time to prepare for the hearing. The  defendant's sentencing date was set for August  19, 1998.


26
Before the defendant was sentenced, Clavelli  filed a motion with the district court seeking to  withdraw as the defendant's counsel. During the  hearing on this motion, Clavelli informed the  district court that he and the defendant had  differences of opinion about the case that could  not be resolved. At this point, the district  court informed the defendant that it was not  going to appoint another lawyer to represent the  defendant and that the defendant had the choice  of proceeding with Clavelli as his lawyer or  proceeding pro se. The defendant resolutely  refused to continue with Clavelli as counsel,  alleging that Clavelli had treated him abusively  and physically attacked him. The district court  then granted Clavelli's motion to withdraw and  both the defendant and the district court  proceeded under the assumption that the defendant  was representing himself.2 When the defendant  requested new counsel at his sentencing hearing,  the district court refused to appoint any further  counsel on the ground that the defendant had been  uncooperative with his previous counsel in an  attempt to drag out his case and in order to  provide a basis for appeal. The district court  further noted that the defendant had been given  the opportunity to proceed with counsel, but  through his own conduct had made that impossible.  The district court therefore refused to delay  sentencing and the defendant was sentenced  without the assistance of counsel.


27
If a criminal defendant seeks to waive his  Sixth Amendment right to counsel, he must do so  knowingly and intelligently. See Johnson v.  Zerbst, 304 U.S. 458, 464-65 (1938). However, "it  is not necessary that the defendant verbally  waive his right to counsel; so long as the  district court has given a defendant sufficient  opportunity to retain the assistance of appointed  counsel, defendant's actions which have the  effect of depriving himself of appointed counsel  will establish a knowing and intentional choice."  Fazzini, 871 F.2d at 642. The district court  appointed four separate lawyers for the  defendant, including one of the four twice. All  of these lawyers either requested to withdraw  because of the defendant's lack of cooperation or  were discharged by the defendant, and the  district court clearly advised the defendant of  the difficulties and dangers of proceeding  without the assistance of counsel, see Faretta v.  California, 422 U.S. 806, 835 (1975) (stating  that a criminal defendant "should be made aware  of the dangers and disadvantages of self-  representation"). Furthermore, the district court  warned the defendant that it would not appoint  another lawyer after Clavelli and gave the  defendant the option to avail himself of counsel  or to proceed pro se. See United States v. Moya-  Gomez, 860 F.2d 706, 739 (7th Cir. 1988) ("A  criminal defendant may be asked to choose between  waiver and another course of action as long as  the choice presented to him is not  constitutionally defective."). In circumstances  such as these, where the defendant's lack of  counsel was caused by his own refusal to  cooperate with the counsel appointed for him and  where the defendant was made aware of the  possible consequences of his refusal to  cooperate, the district court's decision not to  appoint new counsel for the defendant does not  constitute an abuse of discretion. See, e.g.,  United States v. Harris, 2 F.3d 1452, 1455 (7th  Cir. 1993) (finding voluntary and informed waiver  where the defendant refused to cooperate with his  lawyers and was told that no substitute counsel  would be appointed for him).

D.  The Alleged Brady Violation

28
The defendant next contends that the district  court erred in refusing to grant him a new trial  based on the government's alleged failure to  comply with its obligation to turn over  exculpatory material under Brady v. Maryland, 373  U.S. 83, 87 (1963). According to the defendant,  the government violated the requirements of Brady  when it failed to disclose to the defendant  transcripts of statements made by his co-  defendants, Onaro and Chiawan, during their pleas  colloquies. The defendant argues that the  statements made by Onaro and Chiawan at these  plea colloquies were material and exculpatory and  that the district court should have granted the  defendant a new trial based on the government's  suppression of these statements. We review the  district court's denial of the defendant's motion  for a new trial for an abuse of discretion. See  United States v. Kozinski, 16 F.3d 795, 818 (7th  Cir. 1994).


29
In order for the defendant to show that he is  entitled to a new trial because of a Brady  violation, he must demonstrate that: "(1) the  prosecution suppressed evidence; (2) the evidence  allegedly suppressed was favorable to the  defense; and (3) the evidence was material to an  issue at trial." United States v. Walton, 217  F.3d 443, 450 (7th Cir. 2000); see United States  v. Hartbarger, 148 F.3d 777, 786 (7th Cir. 1998).  "Evidence is material only if there exists a  'reasonable probability' that its disclosure to  the defense would have changed the result of the  trial." United States v. Silva, 71 F.3d 667, 670  (7th Cir. 1995); see also Kyles v. Whitley, 514  U.S. 419, 434 (1995) (stating that the  "touchstone of materiality is a 'reasonable  probability' of a different result"). Put another  way, the government's failure to disclose  information that the defendant alleges was  favorable to the defense constitutes a  constitutional violation only if the "supression  [of the evidence] undermines confidence in the  outcome of the trial." United States v. Bagley,  473 U.S. 667, 677 (1985); see United States v.  Asher, 178 F.3d 486, 496 (7th Cir. 1999) ("The  test for materiality of the evidence under Brady  is whether, in the absence of the evidence, the  defendant received a fair trial resulting in a  verdict worthy of confidence.").


30
The defendant's allegations of a Brady violation  focus on the transcripts of testimony given by  Onaro and Chiawan during their plea colloquies on  September 8, 1998. During the course of both of  these colloquies, the government read into the  record an extensive factual basis which indicated  that both Onaro and Chiawan had participated in  a conspiracy to ship drugs from Thailand to the  United States and that the defendant was a part  of that scheme. However, at the point Onaro was  asked if he disagreed with any portion of the  facts recited by the government, he responded: "Lucky and the woman, we did not conspire. I  didn't know Lucky before. Lucky don't know me  before." In addition, when Chiawan was asked if  her role in the conspiracy was "to get the heroin  and give it to [the defendant]," she denied this  role and stated that she "was to come to obtain  the heroin" and that "[t]hey asked me to come and  pick up the money." According to the defendant,  these statements by Onaro and Chiawan were  exculpatory and material and should have been  disclosed to the defendant.


31
Although when viewed in isolation the statements  cited by the defendant are arguably favorable to  the defense, a contextual reading of those  statements undermines the defendant's claim as to  the exculpatory nature of the evidence. Chiawan's  statements simply clarified her own role in the  conspiracy and did not bear directly on the  defendant's participation. Onaro's statements did  partially describe the defendant's role in the  conspiracy, but the statements indicated only  that Onaro did not know the defendant prior to  the beginning of the conspiracy. In light of the  ambiguity reflected in these statements, and the  overall inculpatory nature of the transcripts, it  is not clear that the evidence allegedly  suppressed was the kind of material subject to  disclosure under Brady. See United States v.  Hamilton, 107 F.3d 499, 509 (7th Cir. 1997)  (stating that the government need not disclose  "every possible shred of evidence that could  conceivably benefit the defendant"); see also  United States v. Agurs, 427 U.S. 97, 109-10  (1976) ("The mere possibility that an item of  undisclosed information might have helped the  defense, or might have affected the outcome of  the trial, does not establish 'materiality' in  the constitutional sense.").


32
Even if the statements made by Onaro and  Chiawan could be construed as favorable evidence  that was suppressed by the government, the  defendant's claim of error in regard to the  district court's refusal to grant the defendant  a new trial faces a more substantial obstacle.  When the allegedly exculpatory statements are  read in context and in light of the record as a  whole, it is clear that the undisclosed  transcripts were not material to the defendant's  case. The transcripts themselves, as well as the  factual basis prepared by the government to which  both Onaro and Chiawan assented on the record,  provide strong inculpatory evidence that the  defendant participated in a conspiracy to import  heroin from Thailand. Moreover, in light of the  evidence presented at trial, there is little  probability that the introduction of the disputed  transcripts would have changed the outcome. See  United States v. Olson, 846 F.2d 1103, 1118 (7th  Cir. 1988) (indicating that the materiality of a  particular piece of evidence must be evaluated in  relation to the strength of the other evidence  adduced at trial). Because the defendant has  failed to show that the transcripts he now argues  should have been disclosed to the defense were  both exculpatory and material, we conclude that  the government had no obligation to turn those  transcripts over to the defendant and that the  district court did not abuse its discretion in  denying the defendant's motion for a new trial.

E.  The Indictment

33
The defendant finally challenges the sufficiency  of the indictment returned against him by the  grand jury. The Fifth Amendment provides that  "[n]o person shall be held to answer for a  capital, or otherwise infamous crime, unless on  a presentment or indictment of a Grand Jury . .  . ." U.S. Const. amend V. The defendant contends  that the indictment issued in this case was  defective because it lacked both the signature of  the grand jury foreperson and that of an attorney  for the government.3 According to the  defendant, the failure of the government to prove  that the indictment contained these signatures  renders the indictment void, and consequently  deprives the district court of jurisdiction to  try him for his offenses and makes his trial and  conviction a nullity. We review the sufficiency  of the indictment de novo. See Frank v. United  States, 914 F.2d 828, 830 (7th Cir. 1990).  "Because of [the defendant's] failure to raise  objections to the indictment prior to trial, his  indictment should be upheld unless it is so  defective that it does not, by any reasonable  construction, charge an offense for which the  defendant is convicted." United States v. James,  923 F.2d 1261, 1266 (7th Cir. 1991) (internal  quotation omitted).


34
The Federal Rules of Criminal Procedure state  that indictments are to be signed by both the  foreperson of the grand jury and by an attorney  for the government. See Fed.R.Crim.P. 6(c) ("The  foreperson . . . shall sign all indictments.");  Fed.R.Crim.P. 7(c)(1) ("[The indictment] shall be  signed by the attorney for the government.").  However, precedent of the Supreme Court and of  this Court indicate that both of these signatures  are technical deficiencies that are not  necessarily fatal to the indictment. See United  States v. Wright, 365 F.2d 135, 137 (7th Cir.  1966) ("[T]he signature of the prosecuting  attorney is not an essential part of the  information; nor is improper signing of the  instrument a defect such as to invalidate it.");  Hobby v. United States, 468 U.S. 339, 345 (1984)  ("Even the foreman's duty to sign the indictment  is a formality, for the absence of the foreman's  signature is a mere technical irregularity that  is not necessarily fatal to the indictment.")  (citing Frisbie v. United States, 157 U.S. 160,  163-165 (1895)). Because the alleged failure of  the grand jury foreperson and the attorney for  the government to sign the indictment would be  mere technical deficiencies, and because the  defendant does not allege that the indictment did  not adequately inform him of the charges against  him or otherwise prejudice his defense, the  defendant's challenge to the sufficiency of the  indictment is without merit.

III.  Conclusion

35
Having found no reversible error in the  district court's decisions, we AFFIRM the  defendant's convictions and sentence.



Notes:


1
 In addition to arguing that the evidence was  insufficient for a jury to find him guilty of  conspiracy to import heroin, the defendant  contends that the government failed to present  sufficient evidence of his participation in the  conspiracy to permit the introduction at trial of  hearsay statements made by the defendant's  alleged co-conspirators. Specifically, the  defendant objects to the admission of a tape-  recorded conversation between Onaro and  undercover government agents on March 10, 1998,  as well as a recording of a conversation between  Onaro and a confidential source made on March 31,  1998. We review the district court's  determination that the defendant was a member of  a conspiracy for purposes of the admission of co-  conspirator statements for clear error. See  United States v. Rodriguez, 975 F.2d 404, 411  (7th Cir. 1992).
Ordinarily, a decision as to the admissibility  of co-conspirator statements is made according to  a pre-trial proffer. See United States v.  Santiago, 582 F.2d 1128 (7th Cir. 1978),  overruled on other grounds by Bourjaily v. United  States, 483 U.S. 171 (1987). In order to justify  the admission of a co-conspirator's statement  under Rule 801(d)(2)(E) of the Federal Rules of  Evidence, the government must prove "by a  preponderance of the evidence . . . that (1) a  conspiracy existed, (2) the defendant and the  declarant were members of the conspiracy, and (3)  the statement(s) sought to be admitted were made  during and in furtherance of the conspiracy."  Rodriguez, 975 F.2d at 406. In this case, the  defendant does not question the government's  Santiago proffer, but rather contends that the  evidence adduced at trial did not establish by a  preponderance of the evidence that he was a  member of the conspiracy charged. However, in  light of our conclusion that the evidence was  sufficient to connect the defendant to the  alleged conspiracy, we find this challenge to the  admission of Onaro's statements to be meritless.


2
 When a criminal defendant decides to proceed pro  se, it is generally advisable for the district  court to appoint "shadow counsel" to be available  to assist the defendant if needed. See Hall v.  Washington, 106 F.3d 742, 751 (7th Cir. 1997).  Although the district court did ask Falconer to  remain as the defendant's shadow counsel after  the defendant initially decided to proceed pro  se, the district court did not take any similar  action at the time it allowed Clavelli to  withdraw. While the district court is not  required to appoint shadow counsel, and there is  no allegation that the district court's failure  to do so in this instance resulted in an unfair  process, we urge district courts to appoint  shadow counsel in circumstances where a defendant  decides to proceed pro se. Such an action not  only ensures the availability of counsel to  defendants who decide that proceeding without the  assistance of counsel is not in their best  interest, but also avoids the potential for delay  created by untimely assertions of the right to  counsel.


3
 Although the defendant contends that the original  indictment lacked the signatures of the grand  jury foreperson and an attorney for the  government, the indictment itself has apparently  been lost and is not part of the record on  appeal. However, for the purposes of appeal, we  will assume arguendo that the indictment in fact  lacked the relevant signatures as the defendant  claims.


