Philip Markoff, the man accused of killing a masseuse he’d met through Craigslist, was found dead in his Boston jail cell Sunday, according to Suffolk County law enforcement authorities. The 24-year-old Markoff apparently committed suicide. He was pronounced dead at 10:17 a.m.

The case of Philip Markoff, the accused “Craigslist Killer,” is over after his death this weekend, apparently by his own hand inside Nashua Street Jail. But the questions about why the former Boston University medical student allegedly attacked three women he found on the Internet will never end.

Markoff, who captured national attention during a seven-day crime spree last year, apparently committed suicide during the weekend at the jail.

Markoff, 24, was found unresponsive in his cell and pronounced dead at 10:17 a.m. Sunday. It is unclear if he died Saturday or early Sunday. Saturday would have been his first wedding anniversary. Markoff’s fiancee, Megan McAllister, ended their relationship after visiting Markoff in jail after his arrest in April 2009.

He reportedly cut himself with a razor blade and suffocated under a plastic bag tied around his head.

Markoff was being held without bail at the jail while awaiting trial in Suffolk Superior Court for the murder of Julissa Brisman, 26, of New York City. A tentative trial date of March, 14, 2011, had been set.

Markoff, an upstate New York native, had been living in the Highpoint apartment complex off Quarry Street in Quincy, Mass., when he was arrested in Brisman’s slaying.

In April 2009, he was the target of an intense manhunt.

Investigators received more than 150 tips from people after surveillance images were published of a blond-haired suspect leaving the Copley Marriott shortly after Brisman was shot to death in the doorway of a 20th-floor hotel room.

Police also linked Markoff, who was engaged to be married at the time, to the attack and robbery of a prostitute at the Westin Copley Place.

In Rhode Island, Markoff was indicted for an attack on a stripper during a robbery attempt.

Authorities alleged Markoff arranged to meet all three women through the website Craigslist, where Brisman offered massage services.

Markoff’s alleged involvement in the crimes was discovered, in part, through IP (Internet protocol) addresses that marked physical locations.

Police had Markoff under surveillance at his Quincy apartment for a while. He was driving south on Interstate 95 in Walpole when police stopped his car and asked him to return to Boston police headquarters. He was arrested after questioning.

A book about Markoff’s alleged crimes, “Seven Days of Rage: The Deadly Crime Spree of the Craigslist Killer,” hit bookstores last September. Around the same time, the CBS program, “48 Hours Mystery,” reported on the case.

Boston Police Commissioner Edward Davis and Suffolk County District Attorney Daniel Conley released a joint statement regarding Markoff’s death.

“The investigative steps currently under way are taken in all unattended or unnatural deaths within the city of Boston,” they stated. “Markoff was alone in his cell and all evidence collected thus far indicates that he took his own life.

“Nonetheless, as with all such cases, a comprehensive investigation will be conducted to determine the facts and circumstances surrounding his death.”

Dennis Tatz may be reached at dtatz@ledger.com.