United States Court of Appeals
                            For the Eighth Circuit
                        ___________________________

                                No. 16-2284
                        ___________________________

                             United States of America

                        lllllllllllllllllllll Plaintiff - Appellee

                                           v.

                              Darrell Gene Andersen

                      lllllllllllllllllllll Defendant - Appellant
                                      ____________

                    Appeal from United States District Court
                   for the Northern District of Iowa, Waterloo
                                 ____________

                            Submitted: January 9, 2017
                             Filed: February 17, 2017
                                  [Unpublished]
                                  ____________

Before COLLOTON, MURPHY, and MELLOY, Circuit Judges.
                         ____________

PER CURIAM.

       Darrell Andersen was on supervised release when a sweat patch he wore to
detect drug use showed positive for cocaine and cocaine metabolite. After a hearing
the district court1 determined that Andersen had violated the conditions of his release
and sentenced him to seven months imprisonment. Andersen appeals, and we affirm.

                                          I.

       In May 2004 Darrell Andersen was sentenced to 150 months imprisonment and
eight years of supervised release for drug related offenses. Andersen completed his
term of imprisonment and began supervised release in February 2014. A condition
of Andersen's release was that he refrain from the use of controlled substances. In
March 2016 the United States Probation Office began monitoring Andersen's
compliance with this condition through the use of sweat patches which capture the
wearer's sweat over a period of time. Sweat absorbed by the patch can then be tested
for the presence of controlled substances and their metabolites.

        In April 2016 a sweat patch that Andersen had been wearing for a week was
removed and tested. In an initial test Andersen's patch tested positive for cocaine
metabolite. The presence of cocaine metabolite "indicates that the wearer's body has
broken down cocaine" and is a basis for a conclusion that the wearer has actually used
cocaine. United States v. Meyer, 

, 867 (8th Cir. 2007). A subsequent
test confirmed that cocaine metabolite was present in the sample. The confirmation
test also revealed that the sample tested positive for cocaine. When asked about the
results of the sweat patch tests, Andersen denied using cocaine. He further stated that
while he was wearing the patch he had engaged in sexual intercourse with a woman
who had been using crack cocaine. Andersen suggested that the woman's sweat had
contaminated his patch and caused the positive tests.

     After Andersen's sweat patch tested positive for cocaine and cocaine
metabolite, the government filed a petition to revoke his supervised release. The

      1
      The Honorable Linda R. Reade, Chief United States District Judge for the
Northern District of Iowa.

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district court held a hearing at which a probation officer testified about sweat patch
procedures and the specific results in Andersen's case. Andersen denied that he had
used cocaine and again offered his "sweaty sex" explanation for the positive tests.
The district court determined that the government had established by a preponderance
of evidence that Andersen had violated the terms of his supervised release by using
cocaine. The district court sentenced Andersen to seven months imprisonment and
four years of supervised release. Andersen appeals.

                                           II.

       We review a district court's revocation of supervised release for abuse of
discretion "and its underlying factual findings as to whether a violation occurred for
clear error." United States v. Rhone, 

, 779 (8th Cir. 2011) (internal
quotation marks omitted). We will find that a district court committed clear error
"only if we have a definite and firm conviction that the district court was mistaken."

marks omitted).

       Andersen argues that the district court clearly erred in finding that he had
violated the conditions of his supervised release. Andersen points to two facts in
support of his argument. First, Andersen notes that the confirmation test performed
on his sweat patch indicated merely that cocaine metabolite was "present." Notations
on the test results seem to indicate that there is a difference between a "present" result
and a "positive" result, and that the latter indicates a higher concentration of cocaine
metabolite than the former. Andersen suggests that the lower amount of cocaine
metabolite indicated in the "present" confirmation test result supports his contention
that his patch was contaminated during his sexual activity with a woman who had
been using crack cocaine. Second, Andersen notes that the confirmation test results
indicate that there was significantly more cocaine than cocaine metabolite in the
sample tested. Andersen argues that the ratio of cocaine to cocaine metabolite in his
test results also supports his environmental contamination argument. Andersen

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argues that these facts should have led the district court to conclude that the
government had failed to establish by a preponderance of the evidence that he had
used cocaine.

       We have repeatedly noted that "sweat patch results are a generally reliable
method of determining whether an offender has violated a condition of his or her
probation." 

; see, e.g., United States v. Tolliver, 

, 245 (8th Cir. 2016) (per curiam). We have also noted, however, that "[t]here
may well be certain instances where offenders offer compelling reasons to believe
that positive test results from sweat patches are erroneous." 

.
We must therefore determine whether the evidence and explanations offered by
Andersen are compelling enough to call into question the reliability of the sweat
patch test results in this case. We conclude that they are not.

       With respect to Andersen's first argument, we note that he focuses his attention
entirely upon the second test performed on his sweat patch sample, which he alleges
indicated that cocaine metabolite was merely present. The laboratory also performed
an initial test on Andersen's sweat patch, however, which reflected a "positive" result
for cocaine metabolite. Andersen has given no reason to call into question the
reliability of the first test and its positive result, which would seem to undermine his
contention that a "present" instead of "positive" result on the second test supports his
view that his sweat patch was subject to environmental contamination.

        Even if we were also to focus exclusively on the results of the second test,
however, we would not find the "present" result sufficient to undermine the district
court's determination that the government had proven the supervised release violation
it alleged. A probation officer testified at Andersen's supervised release revocation
hearing that the results of the second test were "a representation confirming that
[cocaine metabolite] was present and it met or was above the threshold" for
establishing a positive test. Andersen offered no evidence to the contrary. Under

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these circumstances, the district court did not clearly err when it relied on the test
results and supporting testimony to conclude that the government had proven by a
preponderance of the evidence that Andersen had violated the conditions of his
supervised release by using cocaine.

       Andersen's second argument also fails to establish clear error by the district
court. In support of his argument that the ratio of cocaine to cocaine metabolite
suggests environmental contamination rather than direct consumption, Andersen cites
expert testimony given in 

. The expert in that case said that
seeing a "certain relative ratio" of controlled substance to metabolite can allow one
to "feel more confident that those test results, in fact, are reflective of actual use of
the drug." Merely pointing out that a certain ratio of controlled substance to
metabolite might mean that it is less likely that a defendant personally used a
controlled substance does not establish that the ratio in this case supports such a
conclusion, however. To the contrary, the laboratory that tested Andersen's sweat
patch concluded that both the first and second tests were positive. We therefore
cannot say that the district court clearly erred when it determined that a
preponderance of the evidence supported the government's contention that Andersen
had violated the conditions of his supervised release by using cocaine.

      Accordingly, we affirm the judgment of the district court.

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