A man has been charged with the death of a woman who advertised massage services on Craigslist, Boston police said.

Philip Marcoff, a 22-year-old Boston University student, was charged with the murder of Julissa Brisman, 29, at the Copley Marriott Hotel and the armed robbery and kidnapping of an additional victim at the Westin Hotel.

Click here for photos from the case.

Boston police say Marcoff has no prior criminal record and is studying pre-med at Boston University. He was stopped on Interstate 95 on the south side of Boston, and was formerly charged Monday evening.

"It appears he was preying on people who are in a vulnerable position ... we are happy to have this man off the street until the investigation is over," said Boston Police Commissioner Ed Davis at a press conference Monday evening.

Davis says authorities had the Boston University student under surveillance "for days" before arresting him.

Police say the charges are based on forensic and electronic evidence developed during an around the clock investigation that will continue through Monday evening and in the weeks and months to come.

Markoff is expected to face arraignment in the Boston Municipal Court Tuesday morning.