A third alleged failed drug test for Nick Diaz was greeted by many in the MMA community with a shrug of the shoulders. As it turns out, though, there is more to the story surrounding his positive test.

The onetime welterweight title challenger and UFC veteran was drug tested three times on the night he fought ex-middleweight champ Anderson Silva at UFC 183. He failed one test for marijuana metabolites, prompting the overseeing Nevada State Athletic Commission to file a complaint in what was his third alleged rule infraction for the drug. A hearing on the matter is pending.

But Diaz, 31, also passed two of the tests administered on Jan. 31, both of which were conducted by the Sports Medicine Research and Testing Laboratory, a WADA-accredited facility in Salt Lake City.

Diaz’s testing documentation in connection with UFC 183, which took place at Las Vegas’ MGM Grand Garden Arena, as well as the NSAC’s complaint and a response by his legal team, were provided by the commission after a public records request by MMAjunkie.

NSAC Executive Director Bob Bennett did not immediately respond to a question requesting clarification on why Diaz was tested three times on fight night, though the fighter was suspended and fined for marijuana by the commission in 2007 and 2012.

According to his UFC 183 testing documents, Diaz was twice tested out-of-competition by the NSAC with the results interpreted by the SMRTL. The WADA lab tested his urine using a “WADA partial menu” for specific performance-enhancers and his blood for human growth-hormone in addition to a “blood passport” examination.

On fight night, however, Diaz’s urine was taken three times and sent to two different laboratories – SMRTL and Quest Diagnostics, the latter of which the NSAC uses to conduct tests for drugs of abuse such as marijuana.

Diaz first gave his urine at 7:12 p.m. – before his UFC 183 headliner – to a collector working on behalf of the SMRTL. The test came back negative when run through a “WADA full menu,” which includes drugs of abuse.

At 10:38 p.m., after his fight, he gave his urine to another collector working on behalf of Quest. The sample ultimately came back showing marijuana metabolites in excess of 300 ng/mL, or double the NSAC’s allowed amount of 150 ng/mL.

Then, at 11:55 p.m., Diaz gave his urine to the same collector for SMRTL. He again passed the WADA full menu.

In its complaint against Diaz, the NSAC cites the Quest Diagnostics findings as the basis for its complaint, also noting the fighter’s failure to disclose his use of marijuana on pre-fight medical paperwork. The test documents from Quest are included as exhibits to the complaint. The SMRTL test results are not.

In a response dated April 9, Diaz, via his legal rep, denied the NSAC’s allegations but did not provide any counterarguments, presumably reserving them for the fighter’s hearing, which is expected to take place in May.

Diaz (26-10 MMA, 7-7 UFC) lost via unanimous decision to Silva (34-6 MMA, 17-2 UFC) in the UFC 183 headliner in his first fight since retiring after a 2012 loss to now-former champ Georges St-Pierre. The loss, however, could be overturned with Silva’s positive test for multiple banned substances. Silva is also expected to appear before the commission in May.

For complete coverage of UFC 183, check out the UFC Events section of the site.