Cops believe the garments are mementoes from the crimes, the Globe reports, and are testing the gun to see if it is the one used to kill masseuse Julissa Brisman, 26. Police also found duct tape, restraints and ammunition in Markoff's apartment, says the Boston Herald.
On Thursday morning, Rhode Island Attorney General Patrick Lynch spokesman Michael Healey told PEOPLE the investigation into whether Markoff attacked a third woman in a Warwick, R.I., hotel on April 16 "has a ways to go."
"At this point it's too early in the investigation to identify Markoff as the guy, but there are strong connections between what happened in Boston and what happened in Rhode Island, and we really can't ignore those connections," Healey said.
The Tip-OffThree homicide investigators – Sgt. Detective Brian Albert, Lt. Det. Robert L. Merner and Serg. Det. Daniel Duff – also described for the newspaper how they caught the 23-year-old Boston University medical student, saying that the biggest lead they received came from a friend of Brisman's.
The friend looked at Brisman's email account the morning she learned of the masseuse's death and saw messages from a man whom Brisman was scheduled to see the night before. The friend forwarded the email to detectives, who were led to an IP address (a computer identification code) that, on Saturday night, was tracked to Markoff's apartment building.
Fears of FleeingStill, they kept Markoff under surveillance, because someone could have logged onto Markoff's home computer and sent the emails. However, on Monday, a victim identified Markoff as her attacker, so the department's fugitive unit staked out his apartment building. There, they saw Markoff and his fiancée, Megan McAllister, leave and, once the couple got in their car, followed them, fearing they were trying to flee.
The investigators pulled the duo over on I-95 in Walpole, Mass., told them the vehicle was being seized through a search warrant and that the couple needed to go to Boston for questioning.
Markoff was "very stoic, very quiet, never asked a question," Merner told the Globe. McAllister was "nervous, confused and full of questions," according to the paper. When informed her fiancé would be charged with murder, "she broke down and cried," the Globe reported.
For more on the Craigslist murder, including the possibly incriminating evidence found in the suspect's apartment, pick up the new issue of PEOPLE, on newsstands Friday