Garfinkel/PoolPhilip Markoff, the alleged 'Craigslist Killer,' was found dead in an apparent suicide in his jail cell, authorities say.

 The Boston medical student who preyed on Craigslist escorts and murdered a Manhattan model last year was found dead in prison Sunday - an apparent suicide on what would have been his first wedding anniversary. 

Philip Markoff, 24, was found dead Sunday morning in his Nashua St. Jail cell in Boston, where he was awaiting his March murder trial. 

He may have died Saturday, the exact anniversary of his canceled wedding. 

A prison source told the Daily News that Markoff was found with a plastic bag over his head, stabbed in the neck and legs. There was a lot of blood. 

Prison officials would not confirm that report. 

A separate source, a guard at the prison, told the News that Markoff's training in anatomy might have helped him beat anti-suicide measures. 

"He's one step beyond other inmates and can do things other inmates can't, because he knows about the human body," the guard told the News. "He's a medical student so if he gets a sharp instrument, he might be able to bleed himself out." 

Markoff was arrested in April 2009 for the murder of Julissa Brisman, 26, a model and aspiring actress from the Upper West Side. 

Brisman, who moonlighted as an erotic masseuse, was shot dead when she fought Markoff's attempts to tie her up and rob her in the plush Marriott Copley Place hotel in downtown Boston. 

Police said Markoff had answered her ad on Craiglist.

When Markoff, a native of upstate New York, was arrested, he was about to start medical school and marry Megan McAllister, his college sweetheart at the University of Albany. 

They had a ritzy Jersey Shore wedding planned for Aug. 14, 2009. 

McAllister initially defended her fiance, telling the media he "couldn't hurt a fly" and was "a beautiful person inside and out." 

Within weeks, as evidence emerged that Markoff had panties and restraints hidden in his boxspring and a handgun hidden in a hollowed-out copy of the medical textbook "Gray's Anatomy" under the bed, she changed her mind and canceled the waterfront wedding in Long Branch, N.J. 

Markoff had been on a brief suicide watch just after his arrest last spring when he reportedly tried to hang himself with his shoe laces and slice his wrists with a sharpened spoon. 

The prison guard told the News that Markoff had no friends in prison and kept to himself in his cellblock, which was restricted to murderers. 

"He secluded himself. He (did) a lot of reading. The other guys are not like him. He's educated; most of these guys come from the street," the guard said. 

Police said the former Boston University medical student robbed escorts on the theory that they would not call the cops. Brisman fought back, so he killed her, cops said. 

Markoff was charged with the armed robbery of another escort in another fancy Boston hotel, and a third assault of an escort at a Rhode Island motel. 

Police said he might have had other victims who were too afraid to come forward, some of them men or transsexuals. 

Police nabbed Markoff after trailing him through cyberspace: tracking his emails, pinpointing the location of his phone calls and watching security camera footage. 

Sadly, Markoff appears to have spawned some copycats. 

A Massachusetts man was arrested just last week for arranging to meet an escort through Craigslist and robbing her. 

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