Police records on Winchester suspect detail odd, threatening behavior

Jeffrey Yao is brought into Woburn District Court, Monday, Feb. 26, 2018 in Woburn, Mass. Yao is arraigned on murder charges and attempted murder after allegedly stabbing a woman to death and attempting to stab a man to death in the Winchester Public Library. (Faith Ninivaggi/The Boston Herald via AP, Pool)
Faith Ninivaggi/The Boston Herald via Associated Press
Jeffrey Yao at Woburn District Court last month.

Winchester police repeatedly brought Jeffrey Yao to the hospital for psychological evaluations over the past several years before he allegedly erupted in violence last month, stabbing a woman to death in the town library, according to two dozen police reports released Wednesday.

The records chronicle Yao’s frequent encounters with police and his wide variety of unsettling, odd, and threatening behavior. He appeared to be suicidal and asked people to kill him. The records hint at treatment Yao was receiving but do not detail how the mental health community handled him.

In one telling incident in late 2016, Yao came to the Winchester Police Department himself, complaining that his therapist was threatening him and that “chemicals coming through the vents in his home” were making him sick.


Police reported the encounter to Yao’s doctor. In a sign of how familiar the troubled young man was to Winchester police, supervisors were asked to tell their officers at roll call “that Jeffrey Yao may be off his meds.”

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Winchester Police Chief Peter MacDonnell said he believes the long record of police interactions with Yao “will create some kind of dialogue on mental health in our society.”

“This situation shows maybe we need to do more,” he said.

Yao, 23, is being held without bail after pleading not guilty to killing Deane Kenny Stryker, a 22-year-old medical student who was studying at the town library on Feb. 24 when Yao allegedly attacked her with a 10-inch knife.

Deane Kenny Stryker.
Deane Kenny Stryker.

Yao’s lawyer, J.W. Carney Jr., said his client was delusional on the day Stryker was killed. Yao was sent last week to Bridgewater State Hospital after a psychiatrist at a county jail concluded he was hearing voices that were telling him what to do, Carney said.


“I commend the Winchester police for how appropriately they dealt with Jeffrey over the years, recognizing that he had serious mental problems,” Carney said. “There is no way anyone could have known that Jeff’s delusions led him to engage in this tragedy. There is certainly nothing that the Winchester police could have done to prevent it.”

Reports related to Yao’s arrest last September for allegedly trying to break into a neighbor’s home were previously made public in a court file. The new batch of reports date back to 2012, when Yao’s erratic behavior alarmed fellow students at Winchester High School.

The Globe reported Feb. 26 that one of Yao’s classmates had reported Yao to the school principal in February 2012, after Yao posted shooting-related materials on social media, including the video manifesto recorded by Seung-Hui Cho, who killed 32 people at Virginia Tech University in 2007.

The police reports released Wednesday shed more light on how school and police authorities responded. After the postings, Yao was required to provide documentation from a psychiatrist that he was safe to be in school.

“Jeffrey Yao has raised the concern of many staff members at WHS as of late,” the reporting officer wrote. “His behavior . . . has been described as ‘very odd.’ ”


Administrators searched Yao’s locker and found nothing troubling. Police searched Yao, too. “Other than some old rotten orange peels in Yao’s sweatshirt pocket, he had no items of concern on him,” police wrote.

A child psychiatrist who saw Yao “did not feel [Yao] was a threat to himself or others” and “cleared him to return to school immediately,” police wrote.

The name of the psychiatrist is redacted from the report. The reports did not say whether Yao had ever been civilly committed to treatment by the courts.

In the fall of 2012, Yao headed for college at Rensselaer Polytechnic Institute, in Troy, N.Y. But school officials asked him to leave on Nov. 2 after numerous problems related to “anti-social behavior” and personal hygiene, according to the reports.

In early 2013, Yao allegedly followed a fifth-grade girl on two occasions, according to the reports, though there was no contact between them.

Two months later, Yao’s father contacted police to say his son was having “mental health issues,” the reports state. Police advised him on the process of legally compelling a person to be evaluated by a psychiatrist.

Police release 911 calls from Winchester library stabbing

On Nov. 13, 2013, Winchester officers transported Yao to the emergency department at Winchester Hospital after his parents said he armed himself with a 6-inch stainless steel knife in the middle of the night and began roaming the house.

Yao’s parents went to the police station to report the incident, saying that they had long clashed over how to help their son but were now seeking assistance.

Yao’s father, Howard, told officers he didn’t confront him because his son doesn’t acknowledge his parents.

Police were told that “it is impossible to communicate with Jeffrey and that confronting him would have been useless.”

While Yao’s parents were at the police station, staff at McLean Hospital in Belmont were notified. Staff said the hospital requires patients be evaluated by an emergency department or crisis team before being admitted.

Officers then went to the family’s home and found Jeffrey asleep on a mat in an unheated attic. Police drove him to the emergency department, where he was met by his parents, who walked him to the registration desk, the report said.

Then in January 2014, a man called Winchester police complaining that Yao was harassing one of his friends on Facebook. The friend, the man said, had just lost her mother in a car crash in New Jersey. In the aftermath, Yao began posting “unkind comments” and photos of fatal car crashes to the woman’s Facebook page. Police said they would document his call, the report said.

That March, police spoke to a resident who complained that Yao was disseminating screen shots of a private online conversation they had three years earlier. The resident said the conversation was about his father being unfaithful. In sharing the exchange, Yao called him a “faggot” and “wannabe gangster,” the resident told police.

Police told the man that he could seek a harassment protection order. The same day, police spoke to another woman who said Yao has two Facebook pages. One page was described as normal, but the other included disturbing images of women being raped, the report said.

On May 30, 2014, police ordered Yao off the grounds of Winchester High School after he interrupted a lacrosse game by running onto the field during play, lifting his shirt and putting it on his head.

In 2016, a woman who lives near Yao called police and reported that while she was away for the weekend, Yao had thrown a shovel that had struck her front door and shattered the window. The report said the woman had been approached by one of Yao’s parents, who offered to pay for the cost of replacing or repairing the door.

She “is aware that Jeffrey has some mental issues, however was still concerned as she has young children who commonly play outside,” the report said.

In March 2016, Yao called police and told an officer that he wanted to turn himself in “because of a crime he committed in Winchester.” Yao told police he had kicked in the door at his home and wanted to be arrested for it the following day, when he would be released from a mental facility, the report said. The name of the facility was redacted from the document.

Police spoke to a nurse at the hospital, who said Yao was nervous about a family meeting planned for the next day. The purpose of the meeting was blacked out.

Later in 2016, a health care worker called police and reported that Jeffrey Yao had made suicidal remarks, saying he was at the library. When police encountered Yao there, he was “lucid and cooperative,” police wrote.

“He stated that people were trying to hurt him but could not specify who these people were,” the report said.

The officer asked him if he would go voluntarily to Winchester Hospital, and Yao agreed. He was admitted.

Before midnight on June 28, 2017, police spoke with a caller from a convenience store who said an Asian man had asked a patron to “do me a favor and kill me.” A short time later, police got a complaint about a man acting strangely inside Andrea’s Pizza, the report said.

Officers went to the restaurant and found Jeffrey Yao.

They brought him outside. Yao asked one officer “if I would kill him” because he had done something bad and “needed to be punished,” the report said.

Yao told police he had hurt someone at his home.

Officers asked him to go to Winchester Hospital voluntarily, and he agreed. After taking Yao to the hospital, police spoke with his father. Howard Yao told police his son asked for money to get food.

He gave him money, the report said, and then Yao left.

Mark Arsenault can be reached at Laura Crimaldi can be reached at