211 F.3d 1022 (7th Cir. 2000)
UNITED STATES OF AMERICA,    Plaintiff-Appellee,v.SAMUEL WHITT,    Defendant-Appellant.
No. 99-2017
In the  United States Court of Appeals  For the Seventh Circuit
Argued January 11, 2000
Decided May 1, 2000

Appeal from the United States District Court  for the Northern District of Indiana, Fort Wayne Division.  No. 95 CR 33--William C. Lee, Chief Judge.
Before COFFEY, EASTERBROOK and EVANS, Circuit Judges.
COFFEY, Circuit Judge.


1
On December 20, 1995, a  federal grand jury sitting in the Northern  District of Indiana returned a one count  indictment charging Samuel Whitt with conspiracy  to distribute cocaine, in violation of 21 U.S.C.  sec. 846. After a jury returned a guilty verdict,  the judge sentenced Whitt to life imprisonment,  five years' supervised release, and a $50 special  assessment. On appeal, Whitt argues that: 1) the  district court erred in not giving the jury an  instruction on a multiple conspiracy; 2) the  indictment was constitutionally defective because  it did not specifically allege the type and  quantity of controlled substances; and 3) the  trial court erroneously calculated the quantity  of drugs for which he was responsible.


2
We affirm.

I.  BACKGROUND

3
Although Whitt was not indicted until 1995, the  genesis of the case occurred in 1992 when the  government charged seven people, including Ruby  Lamb (Ruby), Necole Lamb (Necole), and Helen  Jackson (Helen),1 with conspiring to possess  and distribute cocaine. After Ruby, Necole, and  Helen were convicted by a jury (counsel for the  appellant informed this Court at oral argument  that the other four were acquitted), they  received lengthy prison sentences.2  Understandably unhappy with the prospect of  spending a considerable portion of their lives  behind bars, the three women contacted the  government and agreed to assist in the case  against Whitt in exchange for reduced  sentences.3


4
Although Whitt was not indicted until 1995, the  joint federal, state, and local investigation of  Whitt's and Ruby's criminal activities began in  1990. This investigation revealed that Whitt and  Ruby were the organizers and leaders of a  conspiracy to distribute controlled substances in  the Northern District of Illinois; a conspiracy  which distributed not only cocaine, but heroin  and marijuana as well. And although Whitt was  charged with a conspiracy to distribute  controlled substances between December 1990 and  September 1991, the government believed that  Whitt and Ruby had been involved in the illegal distribution of controlled substances since the  late 1970's or early 1980's.


5
As the leader and organizer of this conspiracy,  Whitt recruited Helen and Necole into the  conspiracy for the purpose of storing cocaine and  heroin at their residences and to distribute  narcotics.4

A.  The Drugs

6
Not only did Whitt recruit individuals to  distribute narcotics for his operation, but he  also personally supplied Necole and Ruby with  cocaine for distribution. According to Necole,  Whitt supplied her with the following amounts of  cocaine for distribution from approximately June  1990 to December 1990:  ounce of cocaine three  times a week, for a total of approximately one  kilogram of cocaine during the last half of 1990.


7
Whitt also supplied Ruby with three to four  bags of cocaine per week from 1990 through April  1991. Each bag contained the following quantities  of cocaine: 10 - one ounce amounts; 10 - 1/2  ounce amounts; 10 - 1/4 ounce amounts; and 10 -  1/8 ounce amounts. Thus, Whitt supplied Ruby with  approximately 57 ounces of cocaine per week; for  a total, averaged over the whole period, of  approximately 108 kilograms of cocaine.5


8
Not only did Whitt supply members of his  organization with drugs, but he also, at times,  sold narcotics directly to customers. During  1991, the investigative agents in this case used  various informants to purchase 1/8 ounce  quantities of cocaine from the defendant for  approximately $200 a buy.6

B.  The Money

9
Further supporting the government's contention  that Whitt was involved in a large drug  operation, law enforcement agents seized  approximately $119,000.00 from Whitt and Ruby in  March of 1990 while the two were at the Miami  International Airport.7 As the sentencing judge  concluded, Whitt has yet to offer a satisfactory  explanation as to how the two of them came into  possession of such a large sum of money,  especially given the fact that neither he nor  Ruby had a visible means of income.


10
In addition, on February 8, 1991, two of the  individuals Whitt recruited into his operation,  Lavon Chandler and John Starkes, Whitt's sister  and cousin, respectively, were stopped near  Daytona Beach, Florida, in Chandler's  automobile.8 After the two agreed to allow the  officers to search the car, police discovered a  suitcase containing $343,540.00 in the trunk of  the vehicle.


11
During the course of the stop, Starkes and  Chandler were placed in the back of a police  squad car. As the two individuals were trying to  decide upon an explanation for the money found in  the trunk of their car, a hidden microphone in  the squad car captured the following conversation  between the two detainees:


12
Chandler: Only thing I know is we just be quiet,  quit acting crazy. When they ask, they said we  had the right to remain quiet, tell 'em we don't  want [to] talk cause we didn't do anything wrong.


13
Starkes: But what attorney we gonna get?


14
Chandler: We can deal with that when we get back  home, now just say it's my money and we don't  want to talk to nobody.


15
Starkes: Say it's yours.


16
Chandler: It don't matter . . . if you wanna say  it's mine you can.


17
Starkes: [Unintelligible]


18
Chandler: All I'm saying is we don't know.


19
Starkes: Okay. We should have talked to Sam. We  should have talked to him and found out what to  do if a situation like this came about.


20
Chandler: Promise me [unintelligible] don't want  anyone to know.9


21
According to the PSR, Whitt offered this rather  lame version of events surrounding the alleged  conspiracy:


22
Mr. Whitt contends that at no time between  December of 1990 and September 4, 1991 [the dates  charged in the indictment], did he join a  conspiracy to distribute controlled substances.  He indicates that he knew the participants who  had been convicted previously of the conspiracy,  but did not have them either working for him or  conspiring with him to violate the controlled  substance law. Mr. Whitt further cannot explain  how his left thumb print was on two of the  baggies in question. He indicates that it could  have been when he visited Helen Jackson's  residence and she cooked dinner for him which  occurred on several occasions during the  operative period. Mr. Whitt further contends that  he did not direct Helen Jackson or [Necole] Lamb  in their drug dealing activities in any manner  whatsoever. The drug ledger involved was kept in  the hand of Helen Jackson and was kept for the  purpose of keeping an account of her sister, Ruby  Lamb's drug inventory.


23
After a two day trial, the jury found Whitt  guilty of conspiracy to distribute cocaine. At  Whitt's sentencing hearing, the government argued  that the defendant was directly responsible,  under the relevant conduct provision of the  guidelines, for at least 607 kilograms of  cocaine. The government, in reaching its drug  calculation, relied heavily on Ruby's testimony  concerning her trips to south Florida with Whitt  to purchase cocaine. Ruby testified that between  1989 and 1992 she traveled with the defendant on  thirty occasions to south Florida and purchased  between 15 and 20 kilograms each trip. The  government further argued that "for sentencing  purposes the government would split the  difference between these two numbers for an  average of 17.5 kilograms of cocaine per each  trip." Because Ruby testified that on one trip  they purchased one hundred kilograms, the  government asserted that the total amount Whitt  was accountable for was at least 607 kilograms  (17.5 x 29 trips = 507.5 kilograms + 100  kilograms = 607.5 kilograms).


24
Whitt, on the other hand, argued that "the  undercover buys by the informants, the amount of  drugs estimated in the ledger, the amount of  drugs seized [from his residence], and the one  statement by Ms. Lamb could form a reliable basis  for determining the drug quantity in this case.  Using that information, the drug quantity would  be approximately 3.5 kilograms--on the generous  side."


25
The district court, in concluding that Whitt  was responsible for over 150 kilograms of  cocaine, determined that Whitt was    conservatively responsible for approximately 21.2  kilograms. Additionally, defendant is responsible  for the amount of drugs seized in the raid. Thus,  to the above sums, must be added 44.6 grams of  heroin, along with 1.6 kilograms of marijuana and  262 grams of cocaine which converts to [a] total  [of] approximately 21.5 kilograms of cocaine.


26
The figure, however, only takes into account  the actual charged period of the conspiracy and  a two month period when [Necole] Lamb resumed  working for the defendant . . . . It does not,  however, account for other relevant conduct.


27
In holding Whitt accountable for additional  quantities of cocaine, the sentencing judge  relied on the testimony of Ruby Lamb, stating  that he believed her testimony despite the fact  that she suffered a nervous breakdown in 1991 and  that some of her testimony was shown to be  incorrect.


28
As mentioned previously, Ruby testified that she  and Whitt purchased 15 to 20 kilograms of cocaine  on 30 different occasions between 1989 and 1991.  Additionally she testified that she went to Los  Angeles on five different occasions in 1990 to  purchase "10 to 15 balls of black tar heroin."  Given the large amounts of narcotics Ruby  testified to, the sentencing judge stated that  "[i]n sum, with respect to the amount of drugs  attributable to the defendant, this Court is of  the view that defendant was responsible for  distribution in excess of 150 kilograms of  cocaine (let alone whatever amount of heroin)  which, for the purposes of the sentencing  guidelines is all that really matters since the  guidelines top off at that level." Whitt appeals.

II.  ISSUES

29
On appeal, we consider: 1) whether the district  court erred by not giving the jury an instruction  on a multiple conspiracy; and 2) whether the  trial court erroneously calculated at sentencing  the quantity of drugs for which Whitt was  responsible.10

III.  DISCUSSION
A.  Multiple Conspiracy Jury Instruction

30
Normally, the finding of the existence of a  single conspiracy is one that this court will  overturn only for clear error. See United States  v. Narvaez, 995 F.2d 759, 762 (7th Cir. 1993).  But, in this case, the defendant did not submit  a multiple conspiracy instruction and we,  therefore, review the issue of whether the trial  court properly gave only a single conspiracy  instruction for plain error. See United States v.  Easley, 977 F.2d 283, 285-86 (7th Cir. 1992). In  order to establish plain error, Whitt must  demonstrate: 1) that error occurred; 2) that the  error was plain; and 3) that the error affected  his substantial rights. See Johnson v. United  States, 520 U.S. 461 (1997).


31
Whitt argues that the evidence does not support  a finding of a single conspiracy; rather, he  argues, the government presented evidence of  multiple conspiracies. Whitt claims that the  court's failure to instruct the jury on multiple  conspiracies thus deprived him of his right to a  fair trial because the jury may have found him  guilty of a conspiracy separate from what was  charged in the indictment.


32
But, we have long held that    [w]hether a single conspiracy exists is a  question of fact; consequently "[t]he jury gets  first crack at deciding 'whether there is one  conspiracy or several when the possibility of a  variance appears.'" United States v. Paiz, 905  F.2d 1014, 1019 (7th Cir. 1990) (quoting United  States v. Percival, 756 F.2d 600, 609 (7th Cir.  1985)). This is because the jury's verdict must  be interpreted as a finding that the government  presented sufficient evidence to prove its  indictment beyond reasonable doubt, and that is  all that we require of the prosecution. The fact  that the government's evidence might also be  consistent with an alternate theory is  irrelevant; the law does not require the  government to disprove every conceivable  hypothesis of innocence in order to sustain a  conviction on an indictment proved beyond  reasonable doubt. United States v. Beverly, 913  F.2d 337, 361 (7th Cir. 1990); United States v.  Douglas, 874 F.2d 1145, 1152 (7th Cir. 1989).  Consequently, "even if the evidence arguably  establishe[d] multiple conspiracies, there [is]  no material variance from an indictment charging  a single conspiracy if a reasonable trier of fact  could have found beyond a reasonable doubt the  existence of the single conspiracy charged in the  indictment." United States v. Prince, 883 F.2d  953, 959 (11th Cir. 1989).


33
United States v. Townsend, 924 F.2d 1385, 1389  (7th Cir. 1991); see also United States v.  Magana, 118 F.3d 1173, 1188 (7th Cir. 1997).


34
Upon review of the record, we hold that,  contrary to the defendant-Whitt's argument on  appeal, the evidence sufficiently supports the  jury's finding of a single conspiracy.  Specifically, the record established a single  purpose, distributing controlled substances,  including cocaine, in the Northern District of  Indiana, to which Whitt, Ruby Lamb, Necole Lamb,  and Helen Jackson all were committed. The  evidence also demonstrates the manner in which  the common goal was met; that is, Whitt and Ruby  Lamb "stashed" and picked-up narcotics at Helen  Jackson's house while Necole Lamb and others  acted as drug runners at the direction of Whitt  and Ruby. As cases like Townsend dictate, the  fact that other theories of criminal conduct may  also be supported by the record does not diminish  the fact that, in this case, the evidence fully  supported a single conspiracy instruction.


35
Whitt also complains that Necole Lamb testified  to events outside the conspiracy charged in the  indictment and that the jury may have therefore  based his conviction on criminal activity not  charged in the indictment. However, Whitt ignores  the fact that at the close of the evidence at  trial the judge instructed the jury that:


36
I want to instruct you, ladies and gentlemen,  that you have just heard evidence of the acts of  the defendant, other than those charged in the  indictment and specifically if you've been  following the dates here, they actually precede  the commencement of the alleged conspiracy which  was December of 1990. So you've just heard  testimony about certain acts of the defendant  that pre-date the opening of the conspiracy. You  may consider the evidence only on the question of  the relationship between the witness and the  defendant and others. This evidence is to be  considered by you only for this limited purpose.


37
(emphasis added). That is, the judge instructed  the jury that it was to consider any evidence  that pre-dated the opening of the conspiracy only  for the limited purpose of establishing the  relationship between the witness, the defendant,  and other relevant individuals, and the jury is  presumed to have followed the court's limiting  instruction. See Doe v. Johnson, 52 F.3d 1448,  1458 (7th Cir. 1995) ("Jurors are presumed to  follow . . . instructions . . . .") (citations  omitted). Thus, the fact that Necole Lamb  testified about her involvement with Whitt prior  to the events alleged in the charged conspiracy  does not establish a separate conspiracy. See  Magana, 118 F.3d at 1188-89.


38
The record clearly supports a finding of a  single conspiracy. Furthermore, Whitt never  submitted a proposed multiple conspiracy  instruction. Thus, we are convinced that the  trial judge did not commit plain error in failing  to instruct the jury on multiple conspiracies.


39
B.  The Trial Court's Calculation of Drug  Quantity


40
On appeal, Whitt asserts that he is responsible  not for the 150 kilograms the sentencing judge  attributed to him, but rather for 3.5 kilograms  of cocaine. In so arguing, Whitt contends that  the judge erred because he relied upon testimony  which was unreliable and that the witnesses were  not credible.


41
However, the guidelines require that    When choosing the base offense level in a  narcotics case, the district court must take into  consideration not only the drug amounts involved  in the offense of conviction, but any that were  part of the same course of conduct or common  scheme or plan as the offense of conviction. This  Court reviews the sentencing court's calculation  of the drug amount only for clear error. We must  be satisfied, however, that the calculation is  based on reliable evidence; speculation and  unfounded allegations will not do.


42
United States v. Pigee, 197 F.3d 879, 889 (7th  Cir. 1999) (internal citations and quotations  omitted).11 Furthermore, "[w]e have  frequently held that the trial judge is in the  best position to judge the credibility of  witnesses who offer conflicting testimony  concerning the quantity of drugs attributable to  a defendant for purposes of sentencing." United  States v. Pitz, 2 F.3d 723, 727-28 (7th Cir.  1993); see also United States v. Mancillas, 183  F.3d 682, 701 n. 22 (7th Cir. 1999) ("We do not  second-guess the [trial] judge's credibility  determinations because he or she has had the best  opportunity to observe the verbal and nonverbal  behavior of the witnesses focusing on the  subject's reactions and responses to the  interrogatories, their facial expressions,  attitudes, tone of voice, eye contact, posture  and body movements, as well as confused or  nervous speech patterns in contrast with merely  looking at the cold pages of an appellate  record." (citation omitted) (brackets in  original)), petition for cert. filed, No. 99-6626  (Oct. 18, 1999).


43
As previously discussed, the court's opinion  explained in detail the facts that it relied on  to reach the 150 kilograms used at sentencing.  All of these facts were gleaned from testimony  which the sentencing judge deemed to be reliable  and credible; specifically Ruby testified that  she and Whitt purchased 15 to 20 kilograms of  cocaine on 30 different occasions between 1989  and 1991, accounting for well over 150 kilograms  of cocaine. Despite Whitt's urging that this  court find the testimony of Ruby, Necole, and  Helen incredible, the fact remains that the judge  concluded, with full knowledge that Ruby had  suffered a nervous breakdown and that some of her  testimony was inaccurate, that her testimony  concerning the amount of cocaine was reliable and  accurate enough to hold Whitt responsible for in  excess of 150 kilograms of cocaine; the maximum  level under the guidelines.12 We know of no  convincing reason, nor has Whitt offered one, to  overturn the district court's credibility  determinations. Thus, we hold that the court did  not commit clear error in determining that Whitt  was responsible for 150 kilograms of cocaine.


44
The decision of the district court is    AFFIRMED.



Notes:


1
 Ruby and Helen are sisters and Necole is Ruby's  daughter.


2
 Ruby received 24 years, Necole received 11  years, and Helen received 31 years.


3
 In exchange for their assistance, the government  filed Rule 35 motions for a reduction in sentence  on behalf of the three women.


4
 Necole testified that although she initially  began to work for the defendant as a "runner,"  she later got on the inside of the operation and  began to work directly with Whitt. Helen  testified that she managed a "stash house" for  the drug conspiracy at the request of the  defendant; a task for which she received $100 a  day. In addition to recruiting Helen and Necole,  Whitt also recruited Lavon Chandler (his sister),  John Starkes (his cousin), Samantha McCall,  Sherrie Hatch, and Kay Shelton into his  organization for the purposes of acquiring and  distributing controlled substances.


5
 During Whitt's trial, the government introduced  Ruby's drug ledger which demonstrated, according  to expert FBI testimony, that Whitt was  responsible for an additional three kilograms of  cocaine. The government therefore estimated that  Whitt was personally responsible for the  distribution of approximately 111 kilograms of  cocaine between June of 1990 and September of  1991. This was in addition to the 1.6 kilograms  of marijuana, the 262 grams of cocaine, and the  44.6 grams of heroin which was seized from his  residence.


6
 These buys occurred on May 15, June 6, June 7,  June 13, June 26, July 2, July 19, and September  3, 1991.


7
 The record does not reflect either how or why  this money was seized.


8
 The record does not reflect why the vehicle was  stopped.


9
 The government believes that this circumstantial  evidence demonstrates that the currency belonged  to the defendant-Samuel Whitt; and during the  sentencing hearing, the judge, based upon the  evidence presented, found that the currency  belonged to Whitt.


10
 Whitt also claims that the amount of drugs he is  to be held responsible for is a matter for the  jury. But because such an argument has  specifically been rejected on numerous occasions  by this court, see, e.g., United States v.  Jackson, 2000 WL 298575, at *9 (7th Cir. March  23, 2000), we decline to consider this issue any  further. See also United States v. Edwards, 523  U.S. 511, 513-14 (1998).


11
 Furthermore, a participant in a drug conspiracy  is accountable for the "reasonably foreseeable  quantities of contraband that were within the  scope of the criminal activity that he jointly  undertook." U.S.S.G. sec. 1B1.3, comment (n.2);  see also United States v. McEntire, 153 F.3d 424,  438 (7th Cir. 1998); United States v. Mumford, 25  F.3d 461, 465 (7th Cir. 1994).


12
 We note that Necole and Helen testified at  Whitt's trial and that the jury also found their  testimony credible.


