A former Boston medical student pleaded not guilty Monday to charges he lured a masseuse he met through Craigslist to a Boston hotel, then bound her, beat her and shot her to death with a gun authorities say he later stashed in a hollowed-out medical textbook.

Philip Markoff firmly stated "not guilty" when asked how he pleaded to the seven charges including kidnapping, armed robbery and weapons violations, then stared straight ahead as prosecutors outlined their case during a brief arraignment in Suffolk Superior Court.

Markoff is charged in the April 14 fatal shooting of Julissa Brisman, 26, of New York City, and the April 10 armed robbery of Trisha Leffler, a 29-year-old Las Vegas prostitute, at another posh Boston hotel. Authorities say he used anonymous e-mail addresses and pre-paid cell phones to set up meetings with the women he met through Craigslist, where they had advertised in its "erotic services" category.

He was ordered held without bail pending trial at the brief hearing. His family refused comment after the hearing.

Click here for photos from the 'Craigslist Killer' case.

Prosecutors say Markoff left a trail linking him to the attacks including his fingerprints on the ties allegedly used to bind the women and on the identification used under another man's name to buy the 9 mm weapon that killed Brisman.

Assistant District Attorney Edmond Zabin said the gun used to kill her was found in a hollowed-out copy of Gray's Anatomy in the Quincy apartment Markoff shared with his then-fiancee, Megan McAllister. McAllister has since called off plans for their August wedding in New Jersey.

They also say Markoff was seen on surveillance video coming and going from the Boston hotels around the times of the attacks.

Brisman's mother, Carmen Guzman, listened in court through a Spanish-speaking translator to how her daughter allegedly fought against her attacker, then was found dead in the entrance of her hotel room with three gunshot wounds to her torso. The family left without answering questions from reporters but issued a statement saying they were "overwhelmed and devastated" by her death.

"She was the light of our lives. She was also a college student who would have graduated this May with a degree in counseling after long hard years of studying and financing" her education, said Jeremy Silverfine, a spokesman for the Guzman family.

Prosecutors have not revealed a motive for the attacks. Markoff was arrested April 20 on Interstate 95 while driving with his fiancee to Foxwoods Resort Casino in Connecticut.

Markoff's attorney, John Salsberg, tried unsuccessfully to persuade Clerk Magistrate Gary Wilson not to allow prosecutors to recite the evidence against Markoff, saying it was unnecessary since Markoff was not fighting for bail and that reciting the evidence against him would only serve to "poison" the potential jury pool for a future trial.

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