BOSTON -- A former medical student accused of killing a masseuse he met through Craigslist scrawled the name of his former fiancee on the wall of his cell, apparently in blood, before committing suicide, authorities said Tuesday.

The name "Megan" and the word "pocket" were found written above the door in Philip Markoff's cell at the Nashua Street Jail in Boston after he was discovered unresponsive Sunday morning, Suffolk District Attorney Daniel Conley said.

Investigators still were trying to determine the meaning of the word "pocket."

Markoff used a pen and a sharp piece of metal to fashion a "primitive scalpel" and used it to inflict several wounds in his neck, arms, wrists and ankles, striking his veins and his carotid artery, Conley said.

He then covered his head and feet with plastic bags that were available to inmates, Conley added. Preliminary autopsy results show the air loss and blood loss combined to kill him, Conley said.

"At this point we can definitively say he's responsible for taking his own life," he said.

While Markoff's death robbed the family of Julissa Brisman of New York City the chance for justice, because Markoff won't go to trial, Conley said the suicide was "the ultimate indicator of consciousness of guilt."

"He won't be tried, but he's far from an innocent man," Conley said, adding that authorities would someday outline for the public the "overwhelming" evidence they had gathered against him.

Surveillance video showed that Markoff was alone in his cell when he turned out the light at 1:59 a.m. Sunday and was discovered dead eight hours later.

Conley said no one entered Markoff's cell during that interval.

Conley said he does not know why Markoff was not on a suicide watch, but authorities are considering that question as part of their investigation.

He said surveillance video at the jail does not extend inside the cells but covers hallways. He said he didn't know whether guards typically wake up inmates during cell checks.