As their investigation continues, police searched the home of Philip Markoff, the 23-year-old medical student who was charged this week with the murder of a woman with whom he allegedly made contact on Craigslist.
Investigators found items of clothing from the victims, and a gun hidden in a hollowed-out book.
Various media outlets cite law enforcement sources who say the victims' undergarments were among items of clothing found in Markoff's home. Neither the Suffolk County District Attorney's Office, nor the Boston Police Department would verify the claim.
But criminologists say it's plausible that such "trophy taking" could fit into a larger pattern of behavior.
"We're certainly seeing misogyny here," says Tom Nolan, a 27-year veteran of the Boston Police Department, and now a professor of criminal justice at Boston University. "This is someone who disdains women, who holds them in a degree of contempt, as is born out by him selecting this particular type of woman."
The Craigslist case throws the spotlight onto what some experts call the "double anonymity" problem of online-sex advertising. Attackers use services like Craigslist to hide their identity from victims, and women advertising on the site usually want to remain anonymous to law enforcement.
Take the murder victim, 26-year-old Julissa Brisman. Jake Wark, spokesman for the Suffolk County District Attorney's Office, says while investigators were led to Markoff's address via e-mails he allegedly sent to her, "e-mails sent to Ms. Brisman in response to her Craigslist ad were received by another individual."
Wark describes that individual as a friend, or someone who was working with Brisman. Wark would not say if the individual was associated with the business aspects of Brisman's postings, saying it is part of the ongoing investigation.
But it's Craigslist — the business — that's come under increasing scrutiny. Connecticut Attorney General Richard Blumenthal said Wednesday the company has a moral obligation to "stop the pimping and prostituting in plain sight."
Craigslist CEO Jim Buckmaster says that would push certain online services onto sites unwilling to cooperate with law enforcement. Craigslist collects phone and credit card numbers with each "erotic services" posting. The company readily provides investigators with that information.
"Because we are so cooperative with law enforcement," Buckmaster says, "we think that criminals are getting the message that choosing Craigslist for criminal activity is an extremely unwise choice, because you're guaranteeing you'll be quickly caught."
Criminologist Tom Nolan believes that's true, but only if a victim comes forward. He says they are often not inclined to do that "partly out of perhaps embarrassment, partly out of the fact that what they're involved in may not necessarily pass legal muster."
A case in point: the Craigslist attacker's first victim who was tied up and robbed. Her name has not been released by investigators, but she talked to WCVB-TV about her reluctance to reveal what she does.
"I mean, my parents don't know what I do," she says. "So, I mean, to find out that way would be horrifying."
And she says even with the media frenzy surrounding this case, what happened to her isn't unusual.
"I've got friends that are in the same business as me, and that have kind of been there."
The woman told WCVB-TV that she no longer advertises on Craigslist. CEO Jim Buckmaster says the company is "a user driven-website" and will continue to allow posts to its "erotic services" section.
This program aired on April 23, 2009.