Prosecutors placed on ad on Craigslist on Thursday, seeking other women who may have been victimized by a medical student accused of killing a woman who advertised her services on the listings Web site.
Suffolk County District Attorney's Office spokesman Jake Wark said that Boston investigators hope the ad, posted in the "erotic services" section of the Web site, will persuade other possible victims to come forth.
Police have said Philip Markoff is believed to have robbed women he initially met on the site.
"Were you attacked or robbed at a Boston-area hotel after placing an ad on Craigslist?" the ad asked.
The posting does not mention Markoff by name, and Wark says investigators aren't sure there are other victims.
Markoff, a Boston University medical student, is charged in the April 14 killing of Julissa Brisman, a 25-year-old masseuse he met through Craigslist. He is also charged in a robbery of another masseuse that police say he met through Craigslist.
Also Thursday, a law enforcement official, speaking to The Associated Press on the condition of anonymity because he was not authorized to discuss the case, said Markoff had been placed on suicide watch at the Boston jail where he is being held. ABC News and The Boston Globe, citing unidentified law enforcement sources, reported that what appeared to be shoelace marks were found on his neck.
Defense attorney John Salsberg told reporters he was concerned about Markoff's well-being but otherwise declined to comment on the reports.
Jail officials declined to comment to The Associated Press, citing privacy rules.
Markoff has pleaded not guilty to charges of murder, armed robbery and kidnapping.
Markoff was arrested Monday in Walpole, less than 20 miles (32 kilometers) southwest of Boston, as he drove with his fiancee, Megan McAllister, to a casino in Connecticut.
Investigators are looking into gambling as the possible motivation. A law enforcement source said Markoff was a "frequent visitor" to Foxwoods casino.
McAllister, who earlier this week said Markoff would not hurt anyone, is standing behind him, her father, James McAllister, told reporters Thursday.
"She's still confident in Phil. Other than that, we're saying a lot of prayers," he said outside his home in Little Silver, New Jersey.
Meanwhile, supporters of Markoff have launched a new Facebook group to rally around him.
The new Facebook group called "Phil Markoff is Innocent Until Proven Guilty" describes itself as a forum to rally against the media and a culture "that has forgotten that people like Phil are suspects, not killers."
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