(CNN) -- Police in Boston, Massachusetts, are searching for a man suspected in the murder of one woman and the armed robbery of two others, all of whom, they say, he may have met through their Craigslist ads for personal services.
Julissa Brisman, 26, was described as "a really sweet, goofy, energetic kid."
Officers discovered New York resident Julissa Brisman, 26, unconscious with multiple gunshot wounds at Boston's Copley Marriott Hotel on Tuesday night. She was transferred to Boston Medical Center, where she died shortly afterward.
Police said Brisman, a model, offered massages via Craigslist, a popular online classified ad service.
The confrontation between Brisman and her killer seems to have begun as an attempted robbery, police said.
"It appears that there was a struggle between the victim and the suspect in the threshold of the hotel room immediately prior to the shooting," the Boston Police Department said in a statement on its Web site.
Police speculate the man may also be responsible for the recent robberies of two other young women who offered personal services via Craigslist.
Four days before Brisman's slaying, a 29-year-old woman was robbed at gunpoint at a Westin Hotel in Boston. Police spokesman Joe Zanola would not disclose the details of her Craigslist ad but said she and Brisman were "involved in similar professions."
On Thursday night at a Holiday Inn Express in Warwick, Rhode Island, a man tied up and demanded money from a 26-year-old dancer who had posted a Craigslist advertisement, according to Warwick's police chief, Col. Stephen McCartney.
The robbery was interrupted when the woman's husband entered the room. After pointing his gun at the husband, the suspect fled, according to McCartney.
He said that no conclusions could be made but allowed that the incident "may be related to similar crimes occurring in the Boston area."
Matthew Terhune, a photographer who met Brisman when he took pictures of her for a calendar last year, described her as "just a really sweet, goofy, energetic kid."
He added that she was enrolled in Alcoholics Anonymous and was contemplating counseling fellow recovering addicts. He had been unaware of her side job as an Internet masseuse.
Surveillance videos from the hotel where Brisman was murdered showed a tall, clean-cut young blond man in a black windbreaker leaving the property, said the Boston Police Department, which is asking the public's help in identifying the man.
Representatives from Craigslist did not respond to a request for comment.