This from the Boston Globe:

Police searching the Quincy apartment of Philip Markoff found underwear from two of the victims in the Craigslist attacks and a handgun hidden in a hollowed-out copy of the medical textbook Gray’s Anatomy of the Human Body, according to a law enforcement official with knowledge of the investigation.

The underpants were described as “mementos” from the crimes, according to another law enforcement official, who also spoke on the condition of anonymity. It was not known from which victims the garments were taken, the officials said. Investigators are testing the gun to determine whether the semi-automatic weapon was used to fatally shoot a 26-year-old masseuse last week at the Boston Marriott Copley Place.

Markoff, 23, is a Boston University medical school student whopleaded not guilty yesterdayto charges stemming from attacks against two women in posh Back Bay hotels. Police in Warwick, R.I., say a prostitute who also advertised on Craigslist was attacked in a hotel there last Thursday,but Markoff has not been charged with that crime. No new victims have come forward so far, one of the law enforcement officials said today.

Authorities have said that his alleged crimes may have been motivated by a gambling problem and a desire to dominate his victims.