217 F.3d 506 (7th Cir. 2000)
United States of America,    Plaintiff-Appellee,v.Roger D. Zehm,    Defendant-Appellant.
No. 99-2495
In the  United States Court of Appeals  For the Seventh Circuit
Argued January 4, 2000Decided June 27, 2000

Appeal from the United States District Court  for the Western District of Wisconsin.  No. 99-CR-1-S--John C. Shabaz, Chief Judge. [Copyrighted Material Omitted][Copyrighted Material Omitted]
Before Cudahy, Kanne, and Diane P. Wood,  Circuit Judges.
Cudahy, Circuit Judge.

I. Facts

1
On January 6, 1999, a grand jury in the  Western District of Wisconsin returned a  four-count indictment against Roger Zehm,  charging him with one count of conspiring  with Trevor Christiansen to distribute  methamphetamine from February 1998 until  early April 1998 and one count of  conspiring with Eric Brown to distribute  methamphetamine from February 1998 until  June 1998. Zehm was also charged with two  counts of distributing methamphetamine--a  total of 4.25 grams--to Cathy Lindstrom  on April 29, 1998 and May 4, 1998. Police  arrested Zehm on January 13, 1999.  Pursuant to a plea agreement, Zehm  pleaded guilty to counts 3 and 4, which  involved the "retail" sales of  methamphetamine. See Appellant's Appendix  B at 4. The trial court dismissed counts  1 and 2, involving the Christiansen and  Brown conspiracies, in which Zehm had  allegedly made "bulk" purchases of  methamphetamine and other drugs that he  would subsequently sell to individual  buyers.


2
Zehm admitted he had been in the  business of dealing drugs for twenty  years. See Appellant's Short Appendix at  7 (Trial Court "Statement of Reasons").  From the third week of February 1998  until early April 1998, Zehm purchased  methamphetamine and cocaine from Trevor  Christiansen. He always paid in cash. As  a rule, Zehm purchased drugs from  Christiansen at Christiansen's home.  After making an initial quarter-ounce  methamphetamine purchase from  Christiansen, Zehm developed a routine in  which he bought three-quarters of an  ounce of methamphetamine every three days  over a six-week period. Zehm purchased  nine ounces of methamphetamine and one  ounce of cocaine over the course of his  relationship with Christiansen. From  February 1998 until June 1998, Zehm also  purchased methamphetamine from Eric  Brown. Again, he began with a relatively  small initial purchase (one ounce), and  then developed a routine in which he  bought two to four ounces of  methamphetamine every other day. Zehm  bought the drugs at Brown's home in  Minnesota, and always paid cash. During  the month of May 1998, Brown was  imprisoned. Scott Wells, who supplied  Brown with methamphetamine, sold directly  to Zehm on Brown's behalf while Brown was  incarcerated. According to the  Presentence Investigation Report, Zehm  purchased 81 ounces total from Brown and  Wells. The district court explained that  Zehm maintained multiple drug suppliers  so that he would have a ready source of  drugs even if a supplier occasionally was  unavailable.


3
During the period Zehm was buying "bulk"  quantities of methamphetamine from Brown,  Wells and Christiansen, he was  distributing the methamphetamine to  individual drug users. Zehm lived in  space adjacent to an auto repair shop  owned by Joel Berg, and his rent payments  consisted of methamphetamine rather than  money. Russell Mork, a steady one-ounce  per month customer of Zehm's, cooperated  with the government after Zehm's arrest.  He told the grand jury that he saw Zehm  distribute methamphetamine to five  people, and said he had been told that  Zehm had been selling a quarter pound of  methamphetamine every day for a month and  a half. See Appellant's Appendix at 75  (Gov't Response to Presentence  Investigation Report, Attachment C, at  1).


4
In March 1998, while Brown and  Christiansen were serving as two of  Zehm's steady suppliers, Zehm met Cathy  Lindstrom at a party. Lindstrom became a  steady half-gram per week customer of  Zehm's. In April 1998, police arrested  Lindstrom for marijuana possession with  intent to distribute. She cooperated with  authorities, and made two controlled  methamphetamine purchases from Zehm on  April 29 and May 4. Zehm had purchased  the methamphetamine sold to Lindstrom  from a third supplier, Jeremy Baker.


5
On May 8, 1998, police executed a search  warrant on Zehm's car. They found 14.6  grams of cocaine, 1.2 grams of  methamphetamine, a loaded .32 caliber  derringer, records of his drug sales to  various individuals, $4,000 in cash and a  cellular phone. Several of Zehm's  customers, as well as Eric Brown and  Trevor Christiansen, testified before the  grand jury about Zehm's drug business.  They furnished details about the quantity  of Zehm's purchases and sales. The trial  court relied on these statements in  determining Zehm's sentence.


6
The trial court sentenced Zehm to two  240-month terms of imprisonment, running  concurrently. In determining the  sentence, the court included as relevant  conduct the 4.25 grams of methamphetamine  Zehm sold to Lindstrom on April 29 and  May 8, to which Zehm had pleaded guilty.  The court also included in Zehm's  relevant conduct his "bulk"  methamphetamine purchases from Brown,  Wells and Christiansen, even though Zehm  had not pleaded guilty to those counts.  The court determined that the bulk  purchases amounted to 90 ounces of  methamphetamine. Zehm contends on appeal  that these purchases should not be  included as relevant conduct.  Additionally, he argues that even if the  trial court was entitled to account for  his purchase from Brown and Christiansen,  it miscalculated the total amount  purchased by 75 ounces because it  erroneously credited Brown's unreliable  testimony. The trial court also denied  Zehm's request for a three-level  reduction for acceptance of  responsibility. Zehm protests this  denial. Finally, the trial court also  determined that the loaded gun found in  Zehm's car warranted a two-level  sentencing adjustment because Zehm  possessed it during the commission of a  drug offense. Zehm challenges these  conclusions.

II. Analysis
A) Relevant Conduct

7
The Sentencing Guidelines instruct that  a defendant's base offense level reflect  the quantity of drugs for which the  defendant is accountable. See United  States v. Griffin, 194 F.3d 808, 826 (7th  Cir. 1999), citing U.S.S.G. sec. 2D1.1.  The base offense level must reflect not  just the amount of drugs involved in the  offense of conviction, but also the  defendant's "acts and omissions . . .  that were part of the same course of  conduct or common scheme or plan as the  offense of conviction." U.S.S.G. sec.  1B1.3(a)(2). We review for clear error  the district court's application of the  so-called "aggregation rule" to determine  drug quantities attributable to relevant  conduct, including both convicted and  unconvicted offenses. See United States  v. Bacallao, 149 F.3d 717, 719 (7th Cir.  1998). The government has a significantly  lighter burden at sentencing than it had  at trial, because it need only prove  relevant conduct by a preponderance of  the evidence, and relaxed evidentiary  rules apply. See United States v.  Crockett, 82 F.3d 722, 729 (7th Cir.  1996). As a measure of restraint,  however, we insist that sentencing courts  "explicitly state and support, either at  the sentencing hearing or (preferably) in  a written statement of reasons, the  finding that the unconvicted activities  bore the necessary relation to the  convicted offense." See United States v.  Beler, 20 F.3d 1428, 1432 (7th Cir.  1994), citing United States v. Duarte,  950 F.2d 1255, 1263 (7th Cir. 1991).


8
The government may prove the necessary  link between the convicted and  unconvicted offenses in two ways. It may  argue that the offenses are part of a  "common scheme or plan." U.S.S.G. sec.  1B1.3(a)(2). Or it may contend that the  offenses are part of the same "course of  conduct." Id. While these two  formulations sound similar, they actually  capture two distinct concepts. Offenses  are part of a common scheme or plan if  they are connected by at least one common  factor, such as "common victims, common  accomplices, common purpose, or similar  modus operandi." See Bacallao, 149 F.3d  at 719, citing U.S.S.G. sec. 1B1.3(a)(2),  Application Note 9. Offenses are part of  the same course of conduct if they are  "part of a single episode, spree, or  ongoing series of offenses." Id. Courts  assessing whether offenses are part of a  course of conduct focus on whether the  offenses were similar, regular, and close  in time. See Bacallao, 149 F.3d at 719.


9
In the present case, the trial court  provided, as required by Beler, a written  statement of reasons, in which it  explicitly identified the basis for its  finding that the unconvicted counts of  bulk drug purchases from Christiansen and  Brown were relevant conduct. See  Appellant's Short Appendix at 7  (Statement of Reasons). It expounded on  its reasoning at sentencing. See  Sentencing Transcript at 19-20. The trial  court found that the unconvicted drug  purchases met both tests for relevant  conduct. "Having multiple sources for his  drugs he turned from Christiansen to  Brown to Wells. His purpose remained the  same--to secure drugs for himself and his  customers . . . . Although defendant was  not convicted of counts 1 and 2, the  conduct embodied therein is included in  the guideline computations because it was  part of the same course of conduct or  common scheme or plan as the offenses of  conviction . . . ." Short Appendix at 7  (Statement of Reasons).


10
Though it purported to find both a  common scheme and a course of conduct,  the trial court's written explanation  identified just one relevant conduct  factor, the common purpose driving the  unconvicted drug purchases and the  convicted drug sales. In its oral  statement, the court identified the  similar modus operandi throughout the  period in question. Common purpose and  similar modus operandi are factors  suggesting a common scheme. Therefore, we  will first review whether the trial court  erred in finding that Zehm's offenses  were part of a common scheme or plan. As  the district court stated, Zehm admitted  to having dealt drugs for two decades.  Zehm appears to have been the  quintessential middleman--purchasing  wares in bulk from suppliers, and selling  them in retail quantities to individuals.  Such "dealing" necessarily requires that  the dealer both buy and sell drugs. Zehm  could not, in other words, have completed  the retail sales for which he was  convicted without first acquiring drugs  from a supplier.  The trial court's brief  explanation captured this essential  reality when it referred to Zehm's  sellers as drug "sources" and, in turn,  to his drug "customers." Courts have  recognized that purchases predating  convicted sales may be considered  relevant conduct. For instance, in United  States v. Vital, 68 F.3d 114, 116 (5th  Cir. 1995), the defendant was convicted  of one count of possession with intent to  distribute cocaine, after he sold 27.7  grams of cocaine to an undercover police  officer. The Fifth Circuit let stand the  trial court's decision to include as  relevant conduct the convicted sale, a  subsequent sale to the same officer one  week later, and thrice-weekly purchases  of cocaine made on the defendant's behalf  in the month preceding the convicted  sale. See id. at 116-18.


11
In the case now before us, Zehm admitted  to a two-decade career as a drug dealer.  Throughout the period in question, he had  regular customers who scheduled routine  drug purchases and therefore he could  calculate the inventory required to meet  demand. Cathy Lindstrom, whose two  purchases gave rise to Zehm's conviction,  purchased a half gram of methamphetamine  from Zehm weekly. Russell Mork purchased  one ounce of methamphetamine from Zehm  every month, and testified that Zehm had  been selling a quarter pound of  methamphetamine daily for the six weeks  prior to his arrest. Zehm even made his  monthly rent payments in methamphetamine.  This steady, predictable demand was  fueled by a steady, predictable supply  from Christiansen and Brown (and Brown's  stand-in, Wells). Zehm purchased three-  quarters of an ounce of methamphetamine  every three days from Christiansen, and  two to four ounces of methamphetamine  every other day from Brown. The routine  weekly sales to Lindstrom would not have  been possible, in light of the high  demand for Zehm's product, without the  steady, reliable supply provided by  Christiansen and Brown.1 Thus, a  common purpose--maintenance of a high-  volume drug distributorship--propelled  both the convicted retail sales and the  unconvicted bulk purchases. Further, as  the sentencing court noted, Zehm's modus  operandi throughout the relevant time  period was similar. He drove to the homes  of his suppliers on a predictable,  frequent schedule and paid in cash for  small, fixed amounts of drugs. He then  sold the drugs in regular quantities to  repeat customers. Based on these two  factors--commonality of purpose and  similarity of modus operandi--the trial  court did not clearly err in counting the  purchases from Christiansen and Brown in  Zehm's relevant conduct.


12
The trial court also concluded that the  evidence was sufficient to prove that all  the offenses were part of a course of  conduct. The court's written explanation  does not identify any factors supporting  this conclusion. But at the sentencing  hearing, the judge stated that "[h]e  purchased methamphetamine from  Christiansen, Brown, and then he resold  the methamphetamine. All of this was the  same course of conduct. . . . He  purchased it from suppliers, whether it  be Christiansen or whether it be Brown or  whether it be a subsequent supplier.  There was regularity, proximity between  the counts of conviction and his  methamphetamine dealing with Christiansen  and Brown." Sentencing Tr. at 19. A  course of conduct involves an ongoing  series of offenses, and courts are to  examine whether the offenses were  similar, regular and close in time. See  Bacallao, 149 F.3d at 719. For instance,  in United States v. Benitez, 92 F.3d 528  (7th Cir. 1996), we affirmed the trial  court's finding that the defendant had  engaged in a "course of conduct"  goingbeyond the offense of conviction;  this extended conduct involved a four-  kilogram cocaine purchase from a  confidential informant. See id. at 539.  During the two years the informant was in  touch with the defendant, she had  frequently discussed the demand for  cocaine and the corresponding police  surveillance of suspected drug dealers.  See id. at 531-32. In addition to several  stray remarks regarding her cocaine  dealing, the defendant on one occasion  remarked that she had seven kilograms of  cocaine in her possession, and at another  time estimated that she could sell up to  eight kilograms in the near future. See  id. at 537, 539. We concluded that the  defendant's ability to calibrate her  cocaine purchases and likely cocaine  sales indicated that the convicted  purchase was part of a course of drug-  dealing conduct. See id. at 538. We  affirmed, finding that the defendant's  revelations to the informant demonstrated  a course of conduct involving at least  five kilograms of drugs. See id. at 538-  39. Similarly, in United States v.  Townsend, 73 F.3d 747, 749 (7th Cir.  1996), a defendant pleaded guilty only to  one count of drug possession. But the  sentencing court heard evidence that he  had been making biweekly drug deliveries  to two distributors for the six months  leading up to his possession offense, and  we affirmed that the drug deliveries were  sufficiently regular to amount to a  course of conduct consistent with his  possession conviction. See Townsend, 73  F.3d at 752.


13
Based on these precedents, we agree with  the trial court that Zehm's drug  purchases and drug sales were an ongoing  series of offenses. Though buying and  selling are, in a sense, dissimilar  activities, they are structurally  symbiotic. As in Benitez, we recognize  that a mid-level drug dealer who  simultaneously estimates impending demand  and tries to procure an adequate supply  is engaged in a course of conduct. One  cannot sell drugs one has not procured.  Further, the trial court in the present  case correctly zeroed in on the  regularity of Zehm's buys. He purchased  every other day from Brown, and every  third day from Christiansen. He routinely  went to their homes to buy drugs, and  always paid in cash. He sold drugs once a  week to Lindstrom, once a month to Mork,  and paid his rent in drugs, in addition  to servicing other customers who  apparently purchased a quarter-pound of  methamphetamine daily. This metronomic  scheduling is similar to the biweekly  sales found regular in Townsend. Finally,  the acts in this ongoing series of  offenses were not just close in time, but  virtually simultaneous. The relevant time  period was February 1998 to June 1998;  during that time Zehm bought drugs on  alternating days from Brown and  Christiansen, and from March to April,  was selling drugs to Lindstrom. Though  the trial court did not explicitly cite  these facts when concluding that Zehm  engaged in a course of conduct, the  record amply supports that finding. In  sum, the trial court did not commit clear  error in finding that Zehm's relevant conduct included the unconvicted  Christiansen and Brown drug conspiracies.


14
Zehm protests the district judge's  relevant conduct calculation on an  additional ground. Even if the sentencing  court was correct to include the Brown  conspiracy, he argues, the court  incorrectly calculated the drug quantity  attributable to that conspiracy. The  trial court determined that Zehm was  responsible for 2.55 kilograms of metham  phetamine, leading to a base offense  level of 34 (reflecting responsibility  for between 1.5 and 5 kilograms of  drugs). Zehm admitted that he purchased  nine ounces of methamphetamine from  Christiansen. Additionally, the trial  court found that Zehm purchased 81 ounces  of methamphetamine in the course of the  Brown conspiracy. Zehm counters that he  purchased just six ounces from Brown.  Again, we review the trial court's  relevant conduct calculation for clear  error. See Griffin, 194 F.3d at 827.


15
Zehm argues that the sentencing court  erred by crediting Brown's allegedly  unreliable testimony in order to arrive  at the 81-ounce figure. Brown testified  that he began dealing with Zehm in March  1998 and continued dealing with him until  June 1998. Further, Lindstrom, Neely and  Mork appeared to corroborate that Eric  Brown was supplying large amounts of  methamphetamine to Zehm on a regular  basis. One witness reported that Zehm had  been purchasing between $4,000 and $8,000  of methamphetamine regularly "from his  source, Eric, in Little Canada,  Minnesota." Presentence Investigation  Report at par. 15. Further, even after  supplier Christiansen's April arrest,  witnesses stated that Zehm continued to  have access to large quantities of drugs,  suggesting that he had found an alternate  supplier. Indeed, one witness stated that  "Roger Zehm is getting [drugs] from Eric  Brown as his source after Christiansen  was arrested." Appellee's Br. at 23.


16
Zehm assails this evidence on many  grounds. He argues that Brown is not a  reliable witness because as the primary  drug supplier in the alleged conspiracy,  "he has the greatest incentive to  fabricate." Appellant's Br. at 21. This  fabrication is evidenced, he argues, by  the fact that Brown did not specifically  state that he stopped dealing drugs to  Zehm either while Zehm was jailed from  May 6 to May 20, or when Brown was jailed  from late May to June 12. It is axiomatic  that the defendant has a due process  right to be sentenced on the basis of  reliable information. See United States  v. Lanterman, 76 F.3d 158, 160 (7th Cir.  1996). But we have stated that the  hallmark of reliability is consistency of  facts and details. See United States v.  Galbraith, 200 F.3d 1006, 1012 (7th Cir.  2000) (collecting cases). The testimony  of just one witness, even a potentially  biased witness, is sufficient to support  a finding of fact. See Galbraith, 200  F.3d at 1012, citing United States v.  Cedano-Rojas, 999 F.2d 1175, 1180 (7th  Cir. 1993). We require only that the  testimony be consistent, or that the  trial judge provide an explanation for  crediting one of the witness's  inconsistent statements over the others.  See Galbraith, 200 F.3d at 1013. For  instance, when witnesses have given  varying estimates of the amount of drugs  they sold or purchased, we have not  permitted the trial judge to credit one  of the amounts without explaining why it  was more believable than the others. See,  e.g., United States v. McEntire, 153 F.3d  424, 436 (7th Cir. 1998); Beler, 20 F.3d  at 1430-33.


17
In the present case, Brown's status as  a government witness and alleged drug  dealer does not sufficiently import bias  so as to undermine the reliability of his  testimony. Further, the "inconsistencies"  Zehm targets are of no moment. The  Presentence Investigation Report flatly  contradicts Zehm's suggestion that Brown  did not admit he ceased dealing drugs to  Zehm during Brown's incarceration. It  reports that "Brown stated that Graig  Wells took over his business while he was  in jail and started dealing to [Zehm]."  Presentence Investigation Report at 6,  par. 23. And while Brown did not  specifically detail the two-week break in  his dealing to Zehm while Zehm was in  jail, he also did not explicitly state  that he dealt drugs to Zehm during the  period in question. Thus, Brown's account  is not overtly inconsistent with reality.  Zehm also charges that Brown incorrectly  stated he began dealing with Zehm in  March 1998, while one witness stated that  "Zehm is getting methamphetamine from  Eric Brown as his source after  Christiansen was arrested [in April]."  Again, this statement is subject to  interpretation. It could well have meant  that although Brown was initially a minor  supplier to Zehm, he expanded his role  when Christiansen suspended business upon  his arrest. In short, nothing said by  Brown or witnesses corroborating his  account was at odds with other witnesses,  or with Zehm's version of events, and  therefore we do not believe that Brown's  testimony should be characterized as  unreliable. The trial judge did not  clearly err in crediting Brown's  testimony or in calculating that Zehm had  purchased 81 ounces of methamphetamine  from Brown. We therefore affirm the trial  court's relevant conduct calculation in  its entirety.

B. Acceptance of Responsibility

18
Zehm asked the sentencing judge to  decrease his sentence to reflect that he  had accepted responsibility for his  crimes, pursuant to U.S.S.G. sec. 3E1.1.  That section provides that a defendant  whose offense level is on par with  Zehm's, and who "clearly demonstrates  acceptance of responsibility for his  offense" should receive a three-point  decrease in his offense level. The  commentary to this provision advises  sentencing judges that they may consider  factors such as


19
truthfully admitting the conduct  comprising the offense(s) of conviction,  and truthfully admitting or not falsely  denying any additional relevant conduct  for which the defendant is accountable  under sec. 1B1.3. . . . A defendant is  not required to volunteer, or  affirmatively admit, relevant conduct  beyond the offense of conviction in order  to obtain a reduction under subsection  (a). A defendant may remain silent in  respect to relevant conduct beyond the  offense of conviction without affecting  his ability to obtain a reduction under  this subsection. However, a defendant who  falsely denies, or frivolously contests,  relevant conduct that the court  determines to be true has acted in a  manner inconsistent with acceptance of  responsibility.


20
U.S.S.G. sec. 1B1.3, Application Note  1(a).


21
The judge denied the reduction, based on  Zehm's challenge to the relevant conduct  calculations. Zehm appeals this denial.  We review for clear error a sentencing  court's factual determination of whether  a defendant has accepted responsibility.  See United States v. Herrera-Ordones, 190  F.3d 504, 511 (7th Cir. 1999); United  States v. Taylor, 72 F.3d 533, 550 (7th  Cir. 1995).


22
We have previously withheld the  acceptance of responsibility deduction  from defendants who deny relevant conduct  in the face of sworn statements from  witnesses or coconspirators tying them to  the offenses in question. For instance,  in Taylor, 72 F.3d at 547-49, the  sentencing court computed relevant  conduct based on the Presentence  Investigation Report. That report, in  turn, relied on statements from "at least  half a dozen individuals with first-hand  knowledge of the drug-distribution  network . . . who . . . gave largely  consistent and mutually-corroborating  accounts . . . [but] provided varying  estimates of drug quantities." See id. at  543. The defendant challenged the  relevant conduct calculation, denying the  statements of witnesses and contesting  the sentencing judge's application of the  aggregation rule. The court subsequently  denied the defendant a reduction for  acceptance of responsibility, stating  that while it is "perfectly appropriate"  for a defendant to contest the amount of  drugs, it was inappropriate to "deny  frivolously" the extent of involvement in  the conspiracy.  Id. at 550. Because the  defendant's story was wholly at odds with  the statements of witnesses, the judge  concluded that her denial was false and  the reduction unwarranted.


23
Zehm's case squares exactly with Taylor.  Zehm contested the judge's application of  the aggregation rule, and denied  responsibility for the full extent of his  involvement in the Brown conspiracy in a  statement wholly at odds with witness  testimony. The sentencing court explained  that the defendant had "falsely denied  and frivolously contested relevant  conduct which the Court has determined to  be true," and therefore did not merit a  sentence reduction. Zehm now argues that  he never denied his part in the Brown or  Christiansen conspiracies, but merely  challenged whether they were relevant to  the offense of conviction. Had he  restricted himself to such legal  maneuvering, we might take a more  favorable view of this matter. But he  also challenged the amount of drugs  attributable to the Brown conspiracy. As  in Taylor, he offered only his bare  denials to counter the largely consistent  stories of several witnesses. The  sentencing court did not clearly err in  finding that Zehm's challenge was  frivolous, and we therefore affirm its  decision to deny the sentence reduction.

C. Possession of Dangerous Weapon

24
On May 8, 1998, four days after Zehm  completed a controlled sale of  methamphetamine to Lindstrom, a confiden  tial informant told police that Zehm  would be picking up about $8,000 worth of  methamphetamine that evening. Police  intercepted Zehm that night, and stopped  his car. He denied police permission to  search the car, but police obtained a  warrant over the phone. They searched the  car and found cocaine and  methamphetamine, drug paraphernalia,  $4,000 in cash and a .32 caliber gun with  two live rounds of ammunition.


25
The district court explained in its  written Statement of Reasons that it  added two points to Zehm's base offense  level because section 2D1.1(b)(1) of the  Sentencing Guidelines requires an  adjustment for possession of a firearm  during an offense. Commentary to the  provision states that "[t]he adjustment  should be applied if the weapon was  present, unless it is clearly improbable  that the weapon was connected with the  offense." Application Note 3. Section  2D1.1(b)(1) requires active or  constructive possession of a firearm. See  United States v. Griffin, 150 F.3d 778,  786 (7th Cir. 1998), citing United States  v. Wetwattana, 94 F.3d 280, 283 (7th Cir.  1996). Constructive possession exists  when a person exercises control over the  firearm. See Wetwattana, 94 F.3d at 283.  For instance, a defendant who sat in the  back seat of a car next to a gun  concealed in a tissue box was held to  have possessed the gun. See id. And when  police impounded a car and found drugs in  the cargo area and a gun concealed in a  briefcase on the floor of the front  passenger seat, we held that the  defendant possessed the gun in connection  with the drug offense. See Griffin, 150  F.3d at 786. Further, a defendant need  not possess the gun during the offense of  conviction, but may possess it during  relevant conduct. See Wetwattana, 94 F.3d  at 283, citing United States v. Anderson,  61 F.3d 1290, 1303-04.  Thus, in United  States v. Mumford, 25 F.3d 461, 468 (7th  Cir. 1994), we affirmed a weapons  enhancement for a defendant whose  coconspirator carried a gun not during  the transaction for which the defendant  was convicted, but during other  transactions considered to be relevant  conduct. See also United States v. Price,  54 F.3d 342, 348 (7th Cir. 1995). We  review the district court's upward  adjustment of a sentence for clear error.  See Wetwattana, 94 F.3d at 283.


26
The relevant conduct period in Zehm's  case extended from February 1 until June  30. The Christiansen conspiracy ended on  April 7, when Christiansen was arrested,  but the Brown conspiracy continued. Thus,  the Brown conspiracy was ongoing on May  8, the date the defendant was found to be  in possession of the weapon. Moreover,  the gun was found in close proximity to  drugs, lending credibility to the trial  court's determination that it was not  clearly improbable the gun was possessed  in connection with the drug offense. See  Sentencing Tr. at 26. Further, according  to the report of a confidential  informant, Zehm was retrieving drugs from  Minnesota when police searched his car  and found the gun. Thus, as in Mumford,  Zehm did possess the gun during the Brown  conspiracy even though he may not have  possessed it during the convicted sales  to Cathy Lindstrom. The trial court did  not clearly err in finding that Zehm  possessed the gun during conduct relevant  to the convicted offenses, and we affirm  its decision to enhance Zehm's base  offense level by two.

III. Conclusion

27
The trial court correctly analyzed and  explained that Zehm engaged in the  unconvicted conspiracy offenses as part  of a scheme or plan and as part of a  course of conduct common with the  convicted drug sales. The trial court  correctly found Brown's testimony  reliable and rightly computed the amount  of drugs attributable to Zehm as a result  of the Brown conspiracy. The court did  not err by denying Zehm an acceptance of  responsibility deduction, because it  soundly determined that Zehm had  frivolously contested the extent of his  relevant conduct. Finally, the trial  court properly enhanced Zehm's sentence  by two levels to reflect the fact that he  possessed a firearm during conduct  relevant to the convicted offenses. We  affirm on all grounds.



Notes:


1
  Zehm contends that the methamphetamine he sold  to Lindstrom in the convicted offenses was  actually purchased from a third supplier, Jeremy  Baker. Thus, neither Christiansen nor Brown was  linked to the convicted sales, he argues. The  provenance of Lindstrom's methamphetamine on the  charged occasions is irrelevant. Zehm worked with  several suppliers in order to satisfy demand in  the Polk County, Wisconsin, area. Had he not  dealt with Christiansen or Brown, the drugs he  purchased from Baker might have been insufficient  to cover all of his customers, including  Lindstrom. So the Christiansen and Brown  conspiracies were essential to the completion of  the convicted sales to Lindstrom.


