The man accused of murdering 26-year-old Julissa Brisman on April 14 and robbing another woman at gunpoint four days earlier was ordered held without bail at his district court arraignment Tuesday, Suffolk County District Attorney Daniel F. Conley announced.

PHILIP MARKOFF (D.O.B. 2/12/86) of Quincy was ordered held without bail at his arraignment Tuesday for Brisman’s April 14 murder in the Marriott Copley Place hotel. Boston Municipal Court Judge Paul K. Leary set bail at $250,000 cash on a separate complaint charging Markoff with the armed robbery and kidnapping of a different woman during an April 10 incident at the Westin Copley Place hotel. Both women had advertised online and were attacked by a man who responded to their postings.

“There may not be any other victims,” Conley said. “But if there are, and if they were initially reluctant to contact investigators for fear that they might be prosecuted, we want to reassure them that our top priority is to hold the assailant – and not his victims – accountable in a court of law.”

Conley said anyone who was robbed or assaulted by a man responding to an on-line posting should contact Boston Police homicide detectives at 617-343-4470, call the CrimeStoppers Tip Line at 1-800-494-TIPS, or text the word “TIP” to CRIME (27463).

Speaking at Tuesday’s proceedings, Assistant District Attorney Jennifer Hickman of Conley’s Homicide Unit told the court that Boston Police homicide detectives had obtained “evidence not only from the crime scenes but also from electronic and cellular communications as well as surveillance videos” from the locations of the two attacks. All of it implicates Markoff, she said.

“There’s a commonality, your honor, between both of these cases – that being that both of these women advertised services on Craig’s List,” Hickman told Leary. “Both of them worked out of hotels in downtown Boston. Both of these women were bound or attempted to be bound. Both of the females were unarmed … A gun was used as well.”

Hickman said the first victim made arrangements to meet a respondent to her online advertisement at the Westin hotel shortly after midnight on April 10 and brought him to her room.

“After shutting the door, she turned around,” Hickman said. “A white male was pointing a gun at her stomach, ordered her to the ground, and, at gunpoint, bound her wrists behind her back.”

Hickman said the assailant spent more than 15 minutes inside the victim’s room, removing more than $800 from her wallet “and taking personal items as well.” Hickman said he bound the victim “to one of the door handles inside the room so she could not escape and put tape over her mouth so she could not scream.”

Hickman said there was internet and cell phone communication between Brisman, the second victim, and the assailant arranging a 10:00 p.m. meeting on April 14. They met at Brisman’s room at the Marriott hotel.

“It appears that Ms. Brisman put up a fight,” the prosecutor said. “She sustained blunt trauma to her skull. She also sustained three gunshots at close range,” including a gunshot wound to the heart that killed her instantly.

“We know from video surveillance that the individual who killed Ms. Brisman walked calmly out of that Marriott Copley hotel,” Hickman told the court.

Hickman also gave details on how investigators identified Markoff as the only suspect in the two cases.

“During the course of the investigation, we’ve been able to track internet information relative to an account used to make one of the appointments,” She told the court. “We were able to track … an email account to an IP address, an internet protocol address, to Philip Markoff at an address in Quincy.”

After developing Markoff’s identity through analysis of the IP address used to make the date with Brisman, Boston Police homicide detectives executed a search warrant at his home late Monday night into Tuesday morning.

“Recovered during the execution of that search warrant was a semiautomatic firearm, as well as ammunition, as well as items that were used or consistent with what was used to bind the victim in the Westin hotel incident and were attempted to be used on Ms. Brisman during the incident at the Marriott Copley.”

Markoff was detained by Massachusetts State Police and MBTA Transit Police in Walpole, Massachusetts, on Monday afternoon as he and his fiancée traveled south on Interstate 95. Both were transported to Boston Police headquarters for interviews. Shortly after 7:00 p.m., Conley authorized a warrant charging Markoff with murder; his fiancée was released.

Markoff is represented by attorney John Salsberg. He will return to court on May 21.