The Michigan Attorney General's Conviction Integrity Unit (CIU) has declined to pursue the release of a man dubbed the “ninja killer” who was convicted of murdering a college student more than 30 years ago.

Temujin Kensu was sentenced to life in prison for the murder of Scott Macklem, who was shot in the parking lot of St. Clair Community College in 1986. Kensu was 23 and practicing martial arts at the time. He became known as the ninja killer after a prosecutor portrayed him as a cunning ninja who was able to hire a plane to fly him from one end of the state to the other, shoot the victim, and return home without a trace.

There is no physical evidence connecting Kensu to the murder, and multiple witnesses said they saw him more than 400 miles away from the scene of the crime that day. In addition, Kensu has insisted he is innocent since the day he was arrested.

Investigators and attorneys recently uncovered additional evidence they claim supports his innocence. But the CIU closed its independent investigation into the case this week after determining there was “no new evidence that supports the factual innocence claim,” according to NBC News.

Kensu is now 58-years-old and has exhausted his appeals and been denied clemency three times. The CIU was his best chance at getting his conviction overturned.

According to NBC News, Kensu believes the CIU has “sentenced me to die in prison for a crime that they know I didn’t commit. That’s not just shameless, it’s criminal.”