James W. Lewis, a suspect in the 1982 Tylenol murders that triggered a nationwide scare over tampered medicine, died Sunday at his home in Cambridge.

In a statement, Cambridge police confirm they were called to Lewis' home Sunday afternoon for a report of an unresponsive person. The police statement says the 76-year-old's death "was determined to be not suspicious."

No one was ever charged with murder for the deaths of seven people in the Chicago area who were poisoned by cyanide-laced Tylenol, but Lewis served more than 12 years for extortion, after sending a note to drugmaker Johnson & Johnson in which he confessed to the poisoning and demanded $1 million.

Despite admitting to sending the extortion letter, Lewis maintained his innocence in the Tylenol poisonings. He said he wanted to embarrass his wife’s former employer by having the money sent to the employer’s bank account.

On a self-published website, Lewis claimed to have been in New York at the time of the murders, rather than in Chicago where the poisonings happened.

When Lewis was arrested in 1982, he gave investigators a detailed account of how the killer might have operated. In a 1992 interview with The Associated Press, Lewis explained that was simply his way of explaining the killer’s actions. “I was doing like I would have done for a corporate client, making a list of possible scenarios,” he told the Associated Press.

Lewis moved to Boston after getting out of prison in 1995.

The FBI seized a computer and other items from Lewis’ home in February 2009 after Illinois authorities renewed the investigation. No charges resulted from that FBI operation. A Chicago area police sergeant last year told The Chicago Tribune that multiple agencies continue to work on the case.

Over the years, Lewis was the subject of a number of other serious allegations and charges. He was charged in a 1978 murder in Kansas City, but that case was dismissed because the victim's cause of death was not determined and some evidence had been illegally obtained.

Lewis was convicted of six counts of mail fraud in a 1981 credit card scheme in Kansas City. In 1982, in addition to being charged with extortion for the Johnson & Johnson letter, Lewis was also charged with sending a threatening letter to President Ronald Reagan.

More recently, he was jailed for three years while awaiting trial on a 2004 kidnapping and rape case in Cambridge, before the charges were dropped because the victim refused to testify.

"He's a psychopath, a textbook psychopath," said Roger Nicholson, who interviewed Lewis twice on Cambridge Community Access TV and has been trying to make a documentary about Lewis. Nicholson stayed in touch with Lewis for years, he said, and even let Lewis stay at his home at one point, despite believing he was responsible for eight murders and a rape.

"He never admitted it, but he said things that were incriminating, incredibly incriminating," Nicholson said.

Nicholson said Lewis described waving to security cameras in New York at the time of the Tylenol poisonings so people would know he was there.

"Why would you need people to know you're in New York?" Nicholson remembers thinking. "You were premeditating an alibi. You're conjuring an alibi. Nobody's looking for you."

Nicholson described Lewis as incredibly smart and "kind of a nerd."

"I liked him overall," Nicholson said. "I liked his personality. That being said, he did some evil stuff."

This story includes reporting from the Associated Press.