If hockey dad Jerry Westrom hadn’t eaten such a messy hot dog at a local ice rink in the sleepy town of Isanti, Minnesota, about 35 miles north of Minneapolis, he might still be a free man today.

But the 52-year-old local businessman is facing charges on Friday for the 1993 murder of sex worker Jeanne Ann “Jeanie” Childs after homicide investigators fished a napkin he used to wipe his mouth from the rink’s concession-stand garbage bin, according to the Minneapolis Star-Tribune.

Investigators were reported to be on to Westrom, who has a string of drunk-driving convictions but nothing more sinister, after he or a close relative submitted DNA to an online genealogy website. Police in Minnesota, emboldened by recent successes in using online genealogy samples to close cold cases, had reopened Child’s murder case and had been scouting through samples through a private company to find a match to forensic evidence left in her Minneapolis apartment in 1993. They found two possible matches. Westrom lived the closest, so they pursued that one first.

Childs was a 35-year-old prostitute who worked out of her Minneapolis apartment around the same time Westrom, who was 27, was working odd jobs in the Twin Cities, according to local press reports. Neighbors living below Childs reported water seeping through their ceiling and called police, who found Childs in her shower with the water still running and her apartment covered in splattered blood. She was wearing only socks, and she had multiple stab wounds, including several that were apparently made after she was dead, according to the case file quoted by local Minneapolis media outlets.

The police collected her semen-stained bed clothes, a T-shirt, bath towels, and a DNA samples from bloodstains, including those found on her bathroom sink. In 1993, Minnesota had not yet allowed DNA evidence to be used in court, and, anyway, they had no databank or feasible way to trace who, of the many men Childs reportedly saw, could have been her killer.

The case was soon closed and considered unsolved.

In 2015, Minneapolis police opened several cold cases that had DNA evidence recorded. The Star-Tribune reports they sent forensic profiles from Childs’ apartment to the state Bureau of Criminal Apprehension (BCA) and to a private DNA company that cross-referenced it with popular online genealogy sites.

Once they were sure that Westrom was one of their primary suspects, they started trailing him to try to get a DNA sample without tipping him off. They needed a clearer match than the private DNA company provided before making the arrest, since using online DNA is not acceptable in a court of law since there is no proof the samples match names provided to these web companies. “If we don’t have a match, we don’t have a case,” Hennepin County District Attorney Mike Freeman said when Westrom was arrested.

The officers then waited for Westrom to do something that would leave a trace. When he ordered a messy hot dog, they pounced. “When discarding something in the trash, the Supreme Court has said many times it is fair game,” Freeman told the Star-Tribune.

It took about a week to match the DNA Westrom left on the napkin to that found in Childs’ apartment—which a judge deemed was enough to get an arrest warrant. Once Westrom was in custody, he was tested again and his DNA was a perfect match, police said.

Westrom denies that he ever knew Childs and has no idea how his DNA got into the dead woman’s apartment. Westrom’s father, Norlin Westrom, told local reporters that his son did, indeed, live in Minneapolis in 1993. His attorney, Steve Meshbesher, did not immediately respond to a request for comment.