Twenty-five years ago, the cannibal serial killer Jeffrey Dahmer met his own demise. Beaten to death Nov. 28, 1994, in a Wisconsin prison by a fellow inmate wielding a metal bar, it was a violent end to a sadistically violent existence.

Dahmer confessed to killing 17 boys and men between 1978 and 1991, when he finally was captured in Milwaukee.

According to federal records that are now part of the Chicago Sun-Times’ growing “The FBI Files” database, investigators’ post-conviction interviews with Dahmer show the questions he was asked and many of his answers were, as might be expected, not for the faint of heart.

It’s been well documented that Dahmer’s murderous spree might have ended sooner and with less carnage had the police been more on-the-ball during encounters with him prior to his 1991 arrest.

But it might have been even sooner, according to a 1992 prison interview with an FBI agent and a police detective in which Dahmer spoke of an incident from the early 1980s. Discharged early from the Army because of his drinking, Dahmer moved to south Florida and, broke, took to sleeping on the beach after working long days at a sandwich shop.

Dahmer told them that one night he was “going back to the beach . . . to the place where I had, you know, my sleeping area set up, and there were some other guys there, and they, I almost got knifed ‘cause they didn’t know who I was. They thought I was trying to rob them or something.”

He also told his interviewers [File 2, pages 183-184]: “I would hate going back to the beach to sleep . . . and so I’d stay up drinking till maybe 3 in the morning, and this one time I got mugged. The guy took a hundred from me.”

Because he was living in Florida at the time 6-year-old Adam Walsh was infamously abducted from a Sears store at the Hollywood Mall and beheaded, Dahmer was asked in the same prison interview whether he had anything to do with the boy’s death.

“Nothing . . . nothing,” Dahmer said, mentioning that he’d come clean about other killings “to clear my conscious of everyone,” so “it wouldn’t make any sense to be trying to hide that.”

When one of the interviewers said maybe he didn’t want to admit killing a child, given that Florida had the death penalty, Dahmer said he wanted to die. “If that would get me the death penalty I’d, I’d admit to it,” he said.

One of the interviewers told him [File 2, pages 186-190], “We want the right person that’s responsible for his murder.”

Dahmer also was asked whether were there “any events in your childhood that you attribute to you for becoming a serial murderer?”

“No, none,” he said.

“The alcohol?” an interviewer asked.

“It’s still a mystery to me, you know, lots of people are big drinkers, and they don’t go out and do this . . . I don’t know,” Dahmer said.

GACY, ALEMAN, CUNANAN, SPECK The Sun-Times’ “The FBI Files” portal also has records on other multiple murderers, including serial killer John Wayne Gacy, mob hitman Harry Aleman, spree killer Andrew Cunanan and mass murderer Richard Speck.

He said he did have a certain type he looked for [File 2, pages 194-195] in potential victims: men who were the “Chip and Dale type” — along the lines of the male striptease Chippendale dancers — with “good looking swimmers type build.”

Asked whether there was “any order you would go in” when dismembering a victim — Dahmer often knocked out his victims with sleeping pills, choked them, cut them apart and sometimes ate their flesh but also held onto body parts — the infamous killer at first seemed unsettled. But soon he opened up in graphic detail: “Just slit from the sternum . . .”

“You’re into necrophilia?” he later was asked.

“Right, and that led to the cannibalism, just one thing led to another,” Dahmer responded.

“The obsession?”

“Right.” [File 2, pages 199-201.]

Dahmer told his interviewers he couldn’t stop killing.

“I was trying everything from grave robbing to actually stealing a mannequin out of a Boston store . . . to placate the desire without having to hurt anybody,” he said.

“But it . . . never worked, and one thing led to another.” [File 2, page 202.]

Dahmer talked about trying to turn victims into “zombies,” toying with the occult and visiting male “striptease acts” in Chicago, where some of his victims came from.

Asked whether he had a religious background when younger, he said: “Although I always felt that there was something more than just this life . . . I never really wanted to think about a religious background because I was involved in such horrible things.” [File 2, pages 203-215.]