Philip Markoff, a former medical student who was accused of killing a masseuse he met through the Web site Craigslist, was found unresponsive in his cell and pronounced dead at about 10:15 a.m. Sunday.
The death is still being investigated, but Markoff was alone in his cell and the evidence indicates he took his own life, according to a statement released by Boston Police Commissioner Edward Davis and Suffolk County District Attorney Daniel F. Conley.
Markoff, 24, was found suffocated with a plastic bag over his head, Boston.com reports.
In June, Markoff pleaded not guilty to charges that in April he lured masseuse Julissa Brisman, 25, to a Boston hotel, then bound her, beat her and fatally shot her.
His attorney, John Salsberg, said Sunday, "I'm shocked and saddened by the news" of Markoff's death.