A sexual predator with a lengthy criminal record who was sought for two years on an arrest warrant out of Maryland committed suicide this summer by swallowing a cyanide pill, authorities say.

Robert Lindsay, 51, had been “on the run” since Aug. 8, 2013, until he was tracked by the U.S. Marshals’ office to a Golden shop, according to Karlyn Tilley, Golden police spokeswoman.

“It’s very seldom when you have someone walking around with their escape clause. It’s not something you see every day,” said Capt. Joe Harvey of the Golden Police Department.

The evidence is conclusive that Lindsay committed suicide by poisoning himself, and that there was no misconduct by any law enforcement agents, Tilley’s news release says.

On July 28, Lindsay tried to elude law enforcement officers when they entered the shop where he was working. Golden police officers ran him down, handcuffed him and placed him in the back seat of a patrol car.

Authorities do not know when he took the pill, which he kept in a pill container with a screw-on top, Harvey said.

“Shortly thereafter, he began sweating profusely and became unresponsive,” Tilley said. “He was taken to the hospital where he later died.”

According to his family, Lindsay had mentioned that he carried a sodium cyanide capsule with him, because he did not want to go back to jail, the news release says.

Cyanide poisoning is so rare that it is not one of the things checked by the coroner’s office, Harvey said. Family members called the coroner and told him he should look for traces of cyanide.

“It was the family who gave us that clue,” Harvey said.

A forensic pathologist determined that sometime between when he was arrested and when he collapsed inside the patrol vehicle, Lindsay swallowed his cyanide pill, Tilley said.

The suspect had a long criminal history out of Maryland including convictions for drugs, violence and as a sexually violent predator, Harvey said.

Kirk Mitchell: 303-954-1206, denverpost.com/coldcases or twitter.com/kirkmitchell