Philip Markoff, the Boston University medical student dubbed the "Craigslist Killer" after he allegedly went on a murderous crime and gambling spree, committed suicide today in jail, officials said.
Steve Tompkins, the chief of external affairs at the Suffolk County, Mass., Sheriff's Deptartment said Markoff died today of apparent suicide at the Nashua Street Jail. He was pronounced dead at 10:17 a.m., Tompkins said.
A statement from the Suffolk County District Attorney's Office said Markoff was alone in his cell and all evidence indicated that he took his own life.
"A comprehensive investigation will be conducted to determine the facts and circumstances surrounding his death," the statement said.
A law enforcement source told ABC News that Markoff was able to take a razor blade from one of the disposable razors jail inmates are allowed to use, and he used it to slash not only his wrists but also the femoral artery in his leg.
He then wrapped the wound in his leg in a garbage bag to conceal the blood, and put another garbage bag over his head and tied it tight around his neck, the source said.
"He didn't come out for breakfast. He didn't come out for morning rec [recreation]. They went in to check on him and he was dead," the law enforcement source said.
"He clearly knew what he was doing," the source said. "He used his medical expertise."
Sources told ABC News that Markoff was being threatened by fellow inmates because he took their canteens playing chess.
Saturday would have been Markoff's first wedding anniversary, had he not been arrested after allegedly attacking and robbing three women he met through ads they had posted online.
He had attempted suicide at least twice before since his arrest, sources have told ABC News.
Markoff, 23, was facing a slew of charges stemming from the murder of masseuse Julissa Brisman, an aspiring drug counselor from New York City who was shot dead in her room at the Marriot Copley Place Hotel on April 14, 2009. Brisman had allegedly booked a "sexual release" massage appointment with the BU medical student that day.
Four days earlier, Markoff allegedly bound and robbed a Las Vegas hooker at the Westin Hotel. And on April 16, 2009, police say he attacked and robbed an exotic dancer at a hotel room in Warwick, R.I. All three victims posted erotic advertisements on the online networking site Craigslist.
Markoff was arrested on April 20, 2009, as he and his fiancée, Megan McAllister, were en route to Foxwoods Casino in Mashantucket, Connecticut, where they had reserved a $88 room for the night.
Evidence linking Markoff to the crimes, including panties from his victims, plastic handcuffs used to bind them and a gun, were found beneath the bed Markoff shared with McAllister.
Days after his arrest -- and as his fiancé attested to his innocence -- Markoff attempted to kill himself at the Nashua Street Jail by pulling leather ties out of his boat shoes to create a small noose that he wrapped around a cell bar. That landed him in a segregated unit for the first 30 days of his incarceration.
At first, McAllister stood by Markoff. She sent an email to ABC News the day after his first suicide attempt defending him and saying the media had the story all wrong.