Investigators searching the apartment of Philip Markoff, the accused murderer now known as the "Craigslist Killer," found a handgun and panties belonging to the two victims hidden in a hollowed-out copy of the textbook Gray's Anatomy of the Human Body, two law enforcement sources told ABC News.
Markoff appeared to be collecting women's panties, which investigators believe were "souvenirs" from his alleged victims, two law enforcement sources said.
Police have asked anyone who may have been contacted by Markoff via Craigslist to come forward, and law enforcement sources told ABC News that detectives investigating the case are now fielding calls from other potential victims.
"There could be none, there could be others," Suffolk County District Attorney Dan Conley told "Good Morning America." "We're not interested in prosecuting them for massage services."
The panties, found hidden in Markoff's apartment and was marked and bagged by police as potential evidence in the case, are one of the reasons investigators believe there could be more victims who have not yet come forward, law enforcement sources said.
Markoff is accused of robbing two women, whom he allegedly lured to upscale hotels through the Web site Craigslist, and killing one of them. He has pleaded not guilty.
Trisha Leffler, who said she was bound and robbed at the Westin Hotel in Boston April 10, told ABC's Boston affiliate WCVB that she immediately recognized Markoff as the man who'd robbed her when she saw him on surveillance photos released by police.
"I hope he will be behind bars for the rest of his life," she said.
Boston police have charged Markoff with the attack against Leffler and for the murder of 26-year-old Julissa Brisman at the Copley Marriott April 14. Both women had placed advertisements on Craigslist.
Leffler, who prosecutors said was robbed of $800, said the only reason she survived is because she didn't fight back. She said she was able to slip her ties shortly after her attacker left the room.
"I just complied with everything he wanted me to do," she said. "I didn't resist him in any way, and that's why."
Police said they believe Markoff's alleged crime spree was an effort to pay off his gambling debts.
Conley said Brisman was beaten very badly and shot three times at close range.
"This was a crime of great violence," he said. "We felt it was a very dangerous man we were looking for."
A wake for Brisman is scheduled for today in New York City.
A source close to the investigation told ABC News that Markoff opened a line of credit at Connecticut's Foxwoods Casino last week. Two days after Brisman was murdered, sources close to the investigation said Markoff hit the casino, leaving with $5,300 in his pocket. Markoff liked to play blackjack and gambled with black $100 chips, the source said.
Markoff and his fiancee Megan McAllister had a room reserved at the Connecticut casino for this Friday and Saturday nights, a source close to the investigation said.
The room was booked in both of their names, and they planned to use Markoff's accrued reward points from his gambling to help pay for it, the source said.
Markoff first applied for a Foxwoods rewards card at the end of 2008 but only went to the casino once that year. Then in March 2009 the visits "grew really frequent,'' the source said.