"Craigslist Killer" Suspect's Dark Side

In an exclusive interview with the New York Daily News, a college friend of alleged "Craigslist Killer" Philip Markoff discussed an incident with him four years ago - possibly fueled by alcohol - which may have provided a glimpse into the medical student's dark side, reports CBS News correspondent Daniel Sieberg.

"He pushed me up against the wall and tried kissing me," Morgan Houston told the paper in the videotaped interview, obtained exclusively by CBS News.

"I couldn't physically get him off of me," Houston told the paper.

Another disturbing turn - woman's underwear belonging to his alleged victims, women who he contacted through their ads for sexual services on Craigslist.com, found in Markoff's Boston residence.

Analysts refer to such items as "souvenirs" from the scene.

Also discovered in Markoff's possession, a hollowed out medical textbook - Gray's Anatomy - with a gun hidden inside.

"I never could have imagined a double-life or that he was capable of using violence to get what he wanted," says James Kehoe, a friend of the suspect.

Markoff stands accused of stalking two women who advertised erotic acts on Craigslist, robbing one and killing another, Julissa Brisman.

A Connecticut casino is cooperating with the investigation, as questions mount over Markoff's possible gambling debts as possible a motive for the alleged attacks.

Meanwhile, a wake was held Wednesday for Brisman - an aspiring model and actress who was found dead with three gunshot wounds.

"At least he's in jail now, you know, and he's going to get what he deserves," said Jennie Guzman, Brisman's cousin.

The Rhode Island Attorney General's office confirms they're preparing to press charges in a similar case in that state in the coming days.