CAMBRIDGE, Mass. — Federal agents today searched the home of a man linked to the fatal 1982 Tylenol poisonings in the Chicago area that triggered a nationwide scare and prompted dramatic changes in the way food and medical products are packaged.

No one was ever charged with the deaths of seven people who took the cyanide-laced drugs. And the FBI would not immediately confirm the search at the home of James W. Lewis was related to the Tylenol case, only that it was part of an ongoing investigation.

Lewis served more than 12 years in prison for sending an extortion note to Johnson &Johnson demanding $1 million to “stop the killing.”

He was arrested in December 1982 at a New York City library after a nationwide manhunt. At the time, he gave investigators a detailed account of how the killer might have operated and described how someone could buy medicine, use a special method to add cyanide to the capsules and return them to store shelves.

Lewis later admitted sending the letter and demanding the money, but said he never intended to collect it. He said he wanted to embarrass his wife’s former employer by having the money sent to the employer’s bank account.

In a 1992 interview with The Associated Press, Lewis explained that the account he gave authorities 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,” said Lewis, who maintained his innocence.

Lewis called the killer “a heinous, cold-blooded killer, a cruel monster.”

He also served two years of a 10-year sentence for tax fraud.

Lewis moved to the Boston area after getting out of prison in 1995 and is listed as a partner in a Web design and programming company called Cyberlewis. On its Web site, which lists the location searched today as the company’s address, there is a tab labeled “Tylenol” with a written message and audio link in which a voice refers to himself as “Tylenol Man.”

“Somehow, after a quarter of a century, I surmise only a select few with critical minds will believe anythng I have to say,” the message says. “Many people look for hidden agendas, for secret double entendre, and ignore the literal meanings I convey. Many enjoy twisting and contorting what I say into something ominous and dreadful which I do not intend.

“That, my friends, is the curse of being labelled the Tylenol Man. Be that as it may, I can not change human proclivities. I shant try. Listen as you like.”

Messages left at phone numbers listed to Lewis’ wife, Leanne, and the company were not immediately returned.

Today, two FBI agents sat parked across the street from the apartment building at a shopping center. At least two other vehicles with Illinois license plates were at the scene.

By afternoon, no law enforcement officials were seen entering or leaving the building — a beige, six-story structure.

In Chicago, FBI spokesman Ross Rice declined to comment but said, “We’ll have something to release later possibly.” A spokesman for the U.S. attorney’s office, Randall Samborn, referred questions to Rice.

Illinois State Police, which were involved with the initial investigation and part of a task force on the killings, declined to comment, referring calls to the FBI office in Chicago.

The Illinois attorney general’s office and Chicago Police could not immediately confirm any details about the investigation, but spokeswomen said they were looking into the matter.

The case has surfaced periodically over the years, primarily in stories marking the anniversary of the killings.

In 2007, 25 years after the deaths, survivors of the victims said they remained haunted by what happened and frustrated that nobody was convicted.

“I will never get past this because this guy is out there, living his life, however miserable it might be,” said Michelle Rosen, who was 8 when her mother, Mary Reiner, collapsed in front of her after taking Tylenol for post-labor pains.