The HONORABLE JOSEPH F. BATAILLON, United States District Judge 1 for the District of Nebraska, sitting by designation. The Honorable David S. Doty, United States District Judge for the District of 2 Minnesota. 

## United States Court of Appeals FOR THE EIGHTH CIRCUIT

___________ No. 97-3450

___________ United States of America, * * Appellee, * * Appeal from the United States v. * District Court for the * District of Minnesota. Flavio Diaz Santana, * * Appellant. *

___________ Submitted: March 10, 1998 Filed: July 24, 1998

___________ Before WOLLMAN and LOKEN, Circuit Judges, and BATAILLON, District Judge. 1

___________ WOLLMAN, Circuit Judge. Flavio Diaz Santana appeals from the judgment entered by the district court on 2 his convictions for conspiracy to distribute and possess with intent to distribute cocaine-2-

in violation of 21 U.S.C. § 846 a nd for aiding and abetting the possession with intent to distribute cocaine in violation of 21 U.S.C. § 841(a)(1). We affirm.

I. In October of 1996, Bill Wyffels, a law enfo rcement officer with the Eden Prairie Police Department and a member of the Southwest Hennepin D rug Task Force, received inf ormation from a confidential informant that a man named Gerardo Arellano wa s sell ing cocaine in Shakopee, Minnesota. After independently corroborating certai n aspects of the informant’s report, Officer Wyffels and other members of the drug task force began surveillance of Arellano’s residence. On October 22, the informant, acting under the direction of the officers, set up a controlled buy in which he was to purchase
one ounce of cocaine from Arellano. Following the successful completion of thi s purchase, the officers obta ined a search warrant for Arellano’s apartment. The officers did not immediately execute the warrant, however, and instead instructed the informant to set up another buy, this time for fifteen ounces of cocaine. The informant contacted Are llano by telephone on October 30. Arellano told the informant that he needed t o contact his s upplier in order to find out if he could obtain the drugs. Arellano calle d back a short time later, telling th e informant that his supplier was delivering the cocaine from Minneapolis and that they could meet in about twenty minutes. The officers set up surveillance around Arellano’s apartm ent. After a short while, they obs erved an automobile approach and come to a stop. The driver, later identified as Diaz, and

a passenger, Timeteo Ruiz, exited the vehicle and accompanied Arellano, who had been waiting outside, into Arellano’s apartment. Arellano and the informant then met as sche duled at a local bar before returning to the apartment. Once inside the apartment, Arellano showed the informant a large plastic sack containing numerou s plastic bags filled with cocaine. After inspecting the drugs, the informant left th e apartment, explaining that he needed to retrieve the money from his vehicle.-3-

The officers then executed the search warrant, discovering during the search a plastic sack, near which Diaz was standing, cont aining fifteen individual packages, each of which co ntained one ounce of cocaine. The officers also discovered 16 grams o f cocaine in the pocket of a shirt hanging in Arellano’s closet and 35.2 grams of cocaine in the trunk of Arellano’s car. The search also resulted in the discovery of $3,449 i n cash. Of this total, Diaz carried $2,059, Ruiz carried $360, and the re mainder was found in t he shirt in Arellano’s closet. In addition, the officers discovered Arellano’s phone numberi n Diaz’s wallet. Lastly, fingerprint analysis of the seized cocaine package s revealed a solitary fingerprint belonging to Diaz. A grand jury returned a

three-count indictment against Arellano, Diaz, and Ruiz. Counts I and III charg ed each defendant with conspiracy to distribute and possess with intent to distribute cocai ne in violation of 21 U.S.C. § 846 and with aiding and abetting the p ossession with intent to distribute cocaine in violation of 21 U.S.C. § 841(a)(1)

. Count I I was returned against Arellano only, and charged him with distribution o f cocaine in v iolation of 21 U.S.C. § 841(a)(1). After the indictment was returned, Ruiz apparently fled the area, and his whereabouts are unknown. Arellano agreed to plead guilty and cooperate with the government. Diaz rejected a similar plea ba rgain, choosing instead to proceed to trial.
Arellano testified that Diaz had been supplying him with cocaine fo r approximately three months, begin ning in August of 1996. A typical delivery consisted of approxi mately two ounces of cocaine. Initially, Arellano received about tw o delive ries per week. The frequency of the deliveries steadily increased as Arellan o began to develop a customer base. By October of 1996, Arellano was receiving twoounce deliveries on a daily b asis. Arellano also testified that on the day of his arrest he had co ntacted Diaz about obtaining fifteen grams of cocaine and that Diaz ha d subsequently delivered the cocaine found in the apartment.-4-

Diaz testified on his own behalf, denying Are llano’s allegations. He testified that he had driven Ruiz to Shakopee as a favor and had no knowledge about the nature o f Ruiz’s dealings with Arellano. He claimed not to have known that Ruiz and Arellano
were involved in a cocaine transaction until shortly before the police arrived, at which time he decided to investigate the contents of the plastic sack. He claimed that he then picked up one of the indivi dual bags, thereby explaining the presence of his fingerprint.

The jury returned a verdict finding Diaz guilty of both charged counts. Th e dist rict court sentenced him to 78 months’ imprisonment, the lowest possible sentence in the applicable range. Diaz now appeals.

II.
Diaz first contends that his trial was marked by numerous defects, includin g prosecutorial misconduct and erroneously admitted expert testimony. We begin with Diaz’s alle gations of prosecutorial misconduct. He contends that statements made and testimony elicited by the government constituted imprope r bolstering of or vouching for Arellano’s credibility. Improp er vouching may occur when the g overnment: (1) refers to facts outside the record or implies that the veracity of a witness is supported by outside facts that are unavailable to the jury; (2) implies a guara ntee of truthfulness; or (3) expresses a personal opinion about the credibility of a witness. See United States v. Beasley , 102 F.3d 1440, 1449 (8th Cir. 1996), cert

. denied , 117 S. Ct. 1856 (1997). Diaz points to t

wo instances of improper vouching. First, the government asked Arellano to explain the terms of his plea agreement, to which Arellano simply replied, “Just to tell thetruth.” Second, the government stated in its closing argument that “the government doesn’t want anyone convicted on anything less than the truth. ” Diaz argues that these instances reflect an attempt on behalf of the government to act as a-5-

guarantor of truthfulness. We disagree. Our decisions establish that “[e]vidence of the existence, the terms, and the witness’s understanding of a plea or witness immunit y agreement is not vouching.” Id. at 1450 ; see also United States v. Magee , 19 F.3d 417, 421 (8th Cir. 1994 ). With respect to the government’s closing remarks, the prosecutor di d not express a personal opinion regarding Arellano’s credibility, did not make an y guarantee s of truthfulness, and did not imply that she knew something that the jury did not. See Bea sley , 102 F.3d at 1449. We therefore conclude that there was n o impermissible vouching in this case.

We hav e considered Diaz’s other allegation of prosecutorial misconduct an d conclude that it is without merit.
Diaz next c ontends that the district court abused its discretion in admitting th e testimony of C aptain Eldon Fontana of the Hennepin County Police Department. Diaz complains that Fontana was improperly allowed to testify regarding the frequency with which fingerprints are recovered from plastic bags. We review a distri ct court’s decision to admit expert testimony for a clear abuse of discretion. See United States v. Chard , 115 F.3d 631, 635 (8th Cir. 1997).

Rule 702 of the Federal Rules of Evidence provides that an expert witness may be qualified “by knowledge, skill, experience, training, or education . . . .” Here , Fontana had twenty-six years of experience in law enforcement, including extensiv e experience in drug-related investigations. The crime lab that performed the fingerprint testing in this case was under his command. Fontana’s experience and knowledg e qualifie d him to testify regarding how common it was for the crime lab to recove r adequate fingerprints from plastic bags. His testimony was relevant and helpful to the jury in that it concerned matters beyond the general knowledge of average individuals. See United States v. Shedlock , 62 F.3d 214, 219 (8th Cir. 1995). Thus, the district court did not abuse its discretion in admitting his testimony.-6- III.

Di az also claims that his trial counsel rendered ineffective assistance. Becaus e ineffective assistance claims generally cannot be established without the developmen t of facts outside the record, t hey should be raised in the context of a proceeding brought under 28 U.S.C. § 2255. See United States v. Hawkins , 78 F.3d 348, 351-52 (8th Cir. 1996) , cert. denied , 117 S. Ct. 126 (1996). We will consider such a claim on direc t appeal only in those exceptional cases in which the district court has developed a record on the ineff

ectiveness issue or where the result would otherwise be a plain miscarriage of justice. See United Sta

tes v. Reddix , 106 F.3d 236, 238 (8th Cir. 1997). This is not such a case, and thus we decline to address the ineffective assistance claim in thi s proceeding.

IV. Diaz argues t

hat his separate convictions for conspiracy to possess cocaine with intent to distribute and for aiding and abetting the possession of cocaine with intent to distribute violated the Double Jeopardy Clause of the Fifth Amendment. Diaz did not raise this claim in the district court, and it is well settled that “[d]ouble jeopardy claims may not be raise d for the first time on appeal.” United States v. Goodwin , 72 F.3d 88, 91 (8th Cir. 1995). In any event, Diaz’s argument is precluded by United States v

. Thomas , 971 F.2d 147 (8th Cir. 1992), which holds that separate convictions identical to those in the present case do not const itute a violation of the Double Jeopardy Clause. 971 F.2d at 149.

V.
Diaz next contends that the evidence was insufficient to support his conviction. When reviewing the sufficiency of the evidence, we view the evidence in the light most favorable to the verdict and give the government the benefit of all reasonable-7-

inferences. See United States v. Diaz-Diaz , 135 F.3d 572, 577 (8th Cir. 1998). We will reverse “‘only if a reaso nable jury must have had a reasonable doubt’ that the elements of the crime were established.” United States v. Carlisle , 118 F.3d 1271, 1273 (8th Cir. 1997), cert. denied , 118 S. Ct. 429 (1997) (quoting United States v. Bordeaux , 84 F.3d 1544, 1547 (8th Cir. 1996)).

Dia z’s argument rests almost exclusively on his assertion that Arellano’ s testimony was not credible and should have been disregarded. Assessing the credibility of witnesses is a matter properly left to the jury. See United St ates v. Anderson , 78 F.3d 420, 422-23 (8th Cir. 1996). The jury heard extensive testimony from Arellan o that Diaz hadsupplied him with a substantial amount of cocaine during August, September, and October of 1996. This testimony, which the jury apparently found credible, was clearly sufficient to support Diaz’s conviction.

VI.
Diaz’s final contention is that the district court made two errors d uring sentencing. First, he argues that his offense level should have been decreased pursuant to U.S.S.G. § 2D1.1(b)(6), which reduces theoffense level for those defendants who qualify for the safety valve exception set forth in U.S.S.G. § 5C1.2. Passing the fact that Diaz raises this is sue for the first time on appeal, his argument is without merit. To qualify for the
sa fety valve exception, a defendant carries the burden of demonstrating that “he ha s truthfully provided to the Government all information regarding the re levant crime before sentencing.” United States v. Velasquez , 141 F.3d 1280, 1283 (8th Cir. 1998); see also U. S.S.G. § 5C1.2(5). There is nothing in the record indicating that Diaz provided any information whatsoever regarding the relevant crime prior to his sentencing.

Diaz asserts that t

he district court erred in calculating the quantity of cocaine for sentencing purposes. We review a district court’s drug quantity calculations for clear-8-

error, and we will reverse only if our examination of the entire record “definitely an d firmly con vinces us that a mistake has been made.” United States v. Moss , 138 F.3 d 742, 745 (8th Cir. 1998) (quoting United States v. Sales , 25 F.3d 709, 711 (8th Cir

. 1994)). Moreover, a district court’s findings regarding the credibility of witnesses “are virtually unreviewable on appeal.” United States v. Karam , 37 F.3d 1280, 1286 (8th Cir. 1994). In arriving at Diaz’s base offense level of 26, the court determined that th e quantity of cocaine attributable to Diaz was at least 500 grams but less than 2 kilograms. Dia z does not dispute that the 476 grams of cocaine seized during the search wer e prope rly attributed to him. However, he argues that the district court erred i n determining that he was accountable for a total quantity of at least 500 grams.

Diaz’s argument is meritless. The district court’s determination was supporte d by the testimony of co-defendant Arellano, who testified that during the course of th e cons piracy he received numerous multi-ounce deliveries of cocaine from Diaz. Tha t testimony, which the court expressly found credible and reliable, was clearly sufficient to justify a quantity determination of more than 500 grams. The judgment is affirmed. A true copy.

Attest:
CLERK, U.S. COURT OF APPEALS, EIGHTH CIRCUIT.