SALEM — A 24-year-old Salem State University student with a history of mental illness stabbed a professor between 20 and 30 times in a men’s bathroom on campus in an apparently unprovoked attack, prosecutors said Thursday.
Around 5:15 Wednesday afternoon, Stephen Chastain came out of a bathroom stall and attacked Pierre Walker, an English professor who was washing his hands.
Walker tried to fight him off, but Chastain strangled him until he passed out, then stabbed him in the neck, chest, arms, and hands with an unidentified object, prosecutors said. Walker regained consciousness and was able to escape from the bathroom, but Chastain continued to stab him.
Walker cried out for help, and two people, including an EMT, rushed to his aid.
Prosecutors described the attack Thursday as Chastain was arraigned on attempted murder and strangulation charges in Salem District Court. A biology major who lives off campus, Chastain pleaded not guilty.
Prosecutors did not provide a motive for the attack, and university officials said there is “no known association” between Walker and Chastain.
After the attack, two witnesses chased Chastain from the building and followed him as he ran across campus. As he ran, he threw his jacket into a barrel and later took off his jeans. He was quickly apprehended by police.
Prosecutors said a knife was found in Chastain’s jacket, but did not say if it was used in the attack. A source familiar with the investigation said a knife was not used, and that Chastain used an aluminum tool, possibly from an art class, as a weapon.
A court-appointed psychologist who evaluated Chastain said he has a history of mental illness and suffers from auditory hallucinations, perceptual distortions, and self-injury.
Judge William Fitzpatrick ordered Chastain sent to Bridgewater State Hospital for a mental health evaluation and scheduled a hearing to determine whether he is competent to stand trial April 19. A separate hearing will be held to assess whether Chastain poses a danger to himself and others.
A medic and nurse who happened to be in the campus building treated Walker, who was expected to be released from the hospital Thursday. Walker is 58 and lives in Beverly, authorities said.
The stabbing was the second on campus since September 2013, when a student on leave from Salem State stabbed a female student on a shuttle bus and wounded the driver.
On campus Thursday, as students hurried to classes, most said they felt safe. But they were divided on whether the university had notified students in a timely manner. Salem State sent a campuswide e-mail more than an hour after the stabbing.
“I got [the e-mail] half an hour after my mother had told me. She saw it on TV,” said Emma Joseph, 20, a social work major from Hopkinton.
John R. Ellement of the Globe staff contributed. Kathy McCabe can be reached at Katherine.McCabe@globe.com.