Authorities say a witness report set off the chain that exposed the death of nurse Janet Swallow.
LYNN, Mass. — A 911 call about a young man walking through a Lynn neighborhood with a knife opened the path to a murder case that investigators say ended with the discovery of 68-year-old Janet Swallow dead in her home in nearby Danvers.
That sequence has become the defining frame of the case against Anthony DeMayo, an 18-year-old Lynn resident and Bishop Fenwick High School senior. Prosecutors say DeMayo pleaded not guilty to murder and armed home invasion in Swallow’s death, and officials have described the killing as random with no known connection between the two. The witness account matters because it was not a marginal detail after the fact. It was the practical turning point that drew police attention, brought a suspect into custody, and connected one city’s report of erratic behavior to another city’s unreported homicide.
Ashley O’Brien, the Lynn woman who called 911, later told local television that the young man she saw was carrying what looked like a large knife and making stabbing motions at bushes. “He looked right in my eyes,” she said, describing a moment that left her feeling he remained intent on hurting someone. Police responded to Standish Road on March 12 and found DeMayo acting erratically with a knife that authorities said had a reddish-brown stain on it. He was taken to Salem Hospital. From there, the case accelerated. Prosecutors told the court and the district attorney later said publicly that DeMayo admitted to officers he had killed a woman in Danvers the night before, a statement that redirected the investigation away from a possible street disturbance and toward a homicide inquiry.
Investigators then worked backward from that encounter. A search warrant at DeMayo’s Lynn home turned up evidence that included blood-stained clothing, according to prosecutors and local reporting. Cellphone data also helped place him in Danvers during a window around midnight into the early morning hours. State police and Danvers officers then went to Swallow’s home on Amherst Street for a well-being check and found her dead with injuries consistent with homicide. Officials later said the suspect and victim were not known to each other. That detail has helped explain why the case first surfaced in Lynn instead of Danvers: until police retraced the defendant’s alleged route, there had been no public report tying the suspect to Swallow’s home.
Only after the Lynn encounter did prosecutors publicly outline what they say happened inside the Danvers house. They allege DeMayo drove through several communities or neighborhoods looking for a place to break into, chose Swallow’s home, entered through a window and found her asleep in bed. Prosecutors said he stabbed her in the neck and left after the attack. Law&Crime, citing court documents first reported by The Boston Globe, said DeMayo told police he had planned to commit such an act for a long time and had wanted to kill someone for a long time. Authorities have not publicly described any theft from the home, and prosecutors said nothing appeared to be missing. That has pushed the case away from theories of burglary gone wrong and toward the prosecution’s claim of a deliberate but random killing.
The impact of those allegations has radiated into several communities at once. Swallow was a longtime Danvers resident and ICU nurse at Lahey Hospital & Medical Center, where colleagues described her as beloved and valued. DeMayo was a senior at Bishop Fenwick in Peabody, where school leaders said the reported incident occurred off campus, did not involve other students and did not pose a threat to the school community. Danvers police also said there was no ongoing threat connected to the homicide. Those responses sought to contain fear, but they also underscored the wide geography of the case: a victim’s home in Danvers, a suspect from Lynn, a school in Peabody, a court in Salem and a hospital in Burlington, all linked by a witness who decided a street encounter was serious enough to report.
The first court appearance did not settle all questions. A psychologist told the judge that DeMayo had depressive symptoms and suicidal ideation and may have had limits in his rational understanding of the proceedings, even though he understood the basics of the case. Judge Joanna Rodriguez ordered him held without bail and sent to Bridgewater State Hospital for a more thorough mental health evaluation. A not guilty plea was entered on his behalf. The district attorney’s office said he was initially due back April 1 for a probable cause hearing, but local reporting later said a grand jury indicted him April 6, moving the matter into Superior Court. Itemlive reported that the next appearance is set for May 11 at 9:30 a.m.
The witness account remains central because it captures the last public sighting before the legal case fully took shape. O’Brien’s decision to call 911 did not solve every question in the case, and authorities still have not publicly answered why Swallow’s home was chosen or what, if anything, beyond the alleged statements will explain motive. But without that call, investigators may have taken longer to connect the suspect, the physical evidence and the body found in Danvers. In that sense, the case is not only about the violence described in court papers. It is also about the narrow moment when one person saw something alarming and acted before the danger disappeared from view.
Anthony DeMayo is still in custody as the case moves into Superior Court, where prosecutors are expected to continue building out the forensic and digital record. The next major public checkpoint is his scheduled May 11 hearing.
Author note: Last updated April 7, 2026.