United States Court of Appeals
                            FOR THE EIGHTH CIRCUIT
                                     ___________

                                     No. 09-2863
                                     ___________

United States of America,                 *
                                          *
       Plaintiff - Appellant,             *
                                          * Appeal from the United States
       v.                                 * District Court for the Southern
                                          * District of Iowa.
Darrell Lee Devries,                      *
                                          *
       Defendant - Appellee.              *
                                     ___________

                                Submitted: April 14, 2010
                                   Filed: January 28, 2011
                                    ___________

Before BYE, JOHN R. GIBSON, and HANSEN, Circuit Judges.
                             ___________

JOHN R. GIBSON, Circuit Judge.

       A jury convicted Darrell Devries of one count each of conspiring to
manufacture methamphetamine, 

(a)(1), 846, and of manufacturing
the drug, 

(a)(1), (b)(1)(B), 

. Devries moved for
judgment of acquittal or, in the alternative, for a new trial on the ground that the
testimony of a co-conspirator was not credible. The district court1 denied the motion
for judgment of acquittal but granted the new trial motion. The government appeals,
arguing that the district court erred in its evaluation of the co-conspirator’s credibility

      1
       The Honorable Robert W. Pratt, Chief Judge, United States District Court for
the Southern District of Iowa.
and that the government presented sufficient additional evidence to sustain a verdict.
We affirm.

       Darrell Devries lived with his girlfriend, Kimberly Pipes, in a rented trailer in
rural Indianola, Iowa. Devries also had permission to use a machine shed located on
the property. On the evening of April 7, 2008, two officers from the Warren County
Sheriff’s Office began conducting surveillance of the trailer and shed from an
adjoining property. They remained until 4:00 or 4:30 on the morning of April 8. A
white pickup truck, which they determined was registered to Sheila Mosset, was
parked on the property when the officers arrived. The only people they saw
throughout their surveillance were Devries and Chris Mosset, Sheila Mosset’s
husband.

       The first activity the officers saw was the white pickup truck leaving at about
midnight. Approximately thirty minutes later the pickup returned, followed by a
“monster truck.” The pickup parked next to the machine shed and the monster truck
parked in the shed, entering through a roll-up door. Chris Mosset was driving the
white pickup truck when it returned, and Devries was driving the monster truck.
Although the officers watched them move about during the next few hours, they could
not tell exactly what the two men were doing because they could not see inside the
machine shed or the trailer. However, one of the officers testified that they observed
what he believed to be the methamphetamine cooking process. As an example, he
noted that the doors on the back side of the shed were open, which would allow fumes
to escape. They saw one of the two men walk out a door of the shed with what
appeared to be a cooler, and they heard banging noises consistent with emptying such
a container. They also heard a loud motor and saw smoke rising from a smokestack
in the shed.

     At about 4:00 or 4:30 a.m., the officers heard a vehicle and saw the taillights of
Mosset’s truck as it was leaving the property. Another officer was alerted and asked

                                          -2-
to make a traffic stop of the truck. When the officer did so, he noticed a strong
chemical odor coming from the cab, one he associated with the manufacture of
m