He waited until he was sure no one was watching, then followed the young woman to the bathroom, prosecutors said. When she came out, she was face to face with the tall, lanky teenager, who immediately attacked.
Philip Chism grabbed the woman by the throat, stabbed her with a pencil, and punched her repeatedly in the face and head, prosecutors said.
In its planning and execution, the June 2 assault was frighteningly similar to the October 2013 rape and slaying of 24-year-old Colleen Ritzer in a bathroom in Danvers High School, where she was a teacher and Chism a student.
But this time the victim survived, saved by co-workers who heard her screams.
Chism, 15, was arraigned in Boston Juvenile Court as a youthful offender Wednesday, accused of attacking a female clinician at the facility where he was being held. Suffolk Assistant District Attorney Mark Zanini said Chism and the unnamed woman had known each other for months. She had been working at the Department of Youth Services facility in Dorchester, where Chism was awaiting trial on charges that he killed Ritzer.
“The defendant’s intent to murder in this case was proven not only by his conduct on June 2, 2014,” Zanini said. “His intent to murder was proven by his conduct in October 2013.”
Chism has pleaded not guilty to Ritzer’s killing. In court Wednesday, the 6-foot-2 teen, dressed in a blue Oxford shirt and khaki pants, kept his head bowed low and his shoulders hunched as Zanini read the allegations against him.
Chism’s mother, Diana, sat behind him, her face obscured by sunglasses, her head also bowed.
Denise Regan, Chism’s court-appointed lawyer, did not argue against bail, which was set at $250,000.
Pleas of not delinquent — the juvenile court equivalent of a not guilty plea — were entered on his behalf. Chism was charged with attempted murder by strangulation, assault with intent to murder, kidnapping, and two counts of assault and battery with a dangerous weapon in the June attack.
Zanini gave a detailed account of the investigation, which was aided in large part by video cameras at the Dorchester facility:
On June 2, Chism, who had been refusing to attend classes, was sitting at a table in a room outside his cell, studying. A male DYS staff member, whose job is to monitor the room, was sitting at a desk behind an eye-level wall, immersed in paperwork.
The staff member failed to notice when Chism moved to a seat closer to the staff hallway, where residents are forbidden from going unless they have permission.
The young clinician walked by. Chism looked at her, then glanced at the staff worker to see whether he was paying attention, Zanini said.
The woman walked into a staff locker room and then into the bathroom.
Chism, holding a pencil in one hand, took off his sandals and kept an eye on the male worker, according to Zanini.
“The staff member was buried in his work,” Zanini said.
Chism crouched down, moved past the counter, which blocked him from the worker, and, still crouched, sneaked into the hallway toward the locker room, according to the prosecutor’s account.
As soon as the woman opened the door, Chism allegedly wrapped his hands around her neck, choking her with such force that she was unable to scream. Chism pushed her against a cinderblock wall as she struggled, Zanini said.
Then, Zanini said, Chism took one hand from her neck and started punching her, which took pressure off her windpipe. The woman was finally able to scream, Zanini said.
When co-workers rushed in, they found Chism pummeling the woman, Zanini continued. They pulled Chism off, and the woman ran out of the room, gasping for air.
There was a rip in her shirt and on her back a “small hole, round in shape,’’ Zanini said. The woman declined medical attention.
Chism seemed psychotic, “screaming incoherently [and] foaming at the mouth,” according to a document filed by DYS in Salem Superior Court. The agency had requested that Chism undergo a psychiatric evaluation after the June 2 assault.
Chism was sent to the Worcester Recovery Center and Hospital, where Essex prosecutors, who are pursuing the murder charges in Danvers, asked for strict security measures.
Prosecutor Kate Berrigan MacDougall told a Superior Court judge after the attack that she was especially worried about any women at the facility.
“I’m not aware of anything that would prevent Mr. Chism from doing exactly what he did on the second, and creeping out of an area and attacking a female staff by herself,” said MacDougall.
State health officials said at that time that Chism would not be alone with staff members, would have his own room, and that at night, staff members would sit at his door. Male staff members would escort him to the bathroom.
Alec Loftus, a spokesman for DYS, declined to say whether the staff worker who was supposed to be watching Chism on June 2 was disciplined, nor would he elaborate on any new security measures made at the Dorchester facility.
“The Department of Youth Services conducted a comprehensive review of this incident and took action to enhance our security procedures to ensure staff and youth are safe at all times,” Loftus said in an e-mail. He added that a staffer has been assigned to monitor Chism at all times.
Chism faces charges of first-degree murder and aggravated rape in the killing of Colleen Ritzer. Just before 3 p.m. on Oct. 22, 2013, Chism, who was a student of Ritzer’s, allegedly followed her into a bathroom at Danvers High School wearing gloves and holding a box cutter.
Essex prosecutors said Chism raped Ritzer, slashed her throat, and stole her cellphone, credit cards, and two driver’s licenses. He is accused of putting her body into a recycling bin and wheeling it into the woods behind the school. He has pleaded not guilty.