A boxer could be facing jail time following his most recent boxing match, thanks to a bloody nose and a resourceful FBI agent.

Martin Tucker, a light welterweight, won his last boxing match, but a bloody cotton swab discarded at the ring was picked up by undercover FBI agent Robert Schmitz, who was investigating a bank robbery.

Schmitz suspected Tucker was involved in a 2009 armed robbery of a credit union in Temperance, Mich. Subsequent tests of the DNA collected from the bloody swab proved his hunch correct, according to court filings.

Tucker, a roofer and part-time boxer, was arrested this week, and ordered held without bail Wednesday. He's accused of using a semi-automatic weapon in the theft of nearly $5,400.

One other man involved in the robbery, Quentin Sherer, was arrested in November 2011.

During his investigation of the robbery, Schmitz began looking through Sherer's social networking profiles and found a picture of Sherer and Tucker together, according to court documents filed by Schmitz. Tucker matched the physical description of the unknown suspect in the 2009 robbery. Schmitz began looking into Tucker.

"In a Myspace Internet search, [Schmitz] learned that Tucker was featured in a boxing match in Toledo, Ohio," the affidavit reads. "During the match, Tucker sustained a bloody nose, and [Schmitz] was able to obtain a discarded Q-tip that contained Tucker's blood."

That Q-tip was submitted to an FBI lab, where it was found that Tucker's DNA matched the DNA found on a mask worn by one of the alleged bank robbers, as well as the steering wheel of the getaway vehicle.

Tucker, who has lost six of his last seven matches, was detained this week, and is scheduled to appear in court at the end of the month.

His attorney, Haytham Faraj, told the Associated Press he wasn't sure that the blood evidence was necessary in this case, but he declined to comment on Tucker's role in the robbery. He did say he sees nothing illegal in Schmitz's recovery of the Q-tip.

"We leave our fingerprints, bits of hair and skin all over the place. If you're a boxer, sometimes you leave your blood around," Faraj told the AP. "It is a dramatic twist. It makes for an interesting read."

Another boxer, Bronco McKart, who was fighting the night Schmitz was ringside, said he was surprised by the allegations how Tucker was caught.

"That's 'CSI Miami' stuff," McKart told the Monroe Evening News, referring to the bloody swab. "That's just amazing."