Macy’s Herald Square stabbing: Suspect who violently attacked woman in bathroom had been released from mental health hospital hours earlier

The suspect accused of stabbing a woman as she changed her child’s diaper inside Macy’s flagship Herald Square store on Thursday had been discharged from a local mental health hospital just hours before the violent attack, prosecutors said Friday.

Kerri Aherne, 24, formerly of Tewksbury, MA, is now locked up in jail after being arraigned in New York Criminal Court on Friday night on a slew of charges, including attempted murder, assault and endangering the welfare of a child for the heinous Dec. 11 attack inside a seventh-floor bathroom inside the renowned department store.

Aherne has a lengthy history of previous mental health trouble, law enforcement sources and published reports indicated. In 2018, she was arrested in her home state of Massachusetts for allegedly threatening to murder Senator Elizabeth Warren, and shooting an individual at a local police station.

In 2024, according to the Manhattan District Attorney’s office, Aherne left Massachusetts while on a temporary leave from the hospital where she had been admitted, and traveled via Uber to New York. Reportedly homeless, she eventually wound up at the Manhattan Psychiatric Center on Randall’s Island, where she had been residing for more than a year until being released on Dec. 11, just a few hours before the violent attack in Herald Square.

Reportedly homeless, Kerri Aherne eventually wound up at the Manhattan Psychiatric Center on Randall’s Island, where she had been residing for more than a year until being released on Dec. 11, just a few hours before the violent attack in Herald Square.Photo via Google Maps

Aherne made sworn statements to police that she had been hospitalized with psychiatric problems for much of her adult life, prosecutors said at her arraignment hearing on Friday night.

The Manhattan Psychiatric Center, in addition to providing inpatient treatment for those with mental illness, also offers short-term housing for those in the hospital’s care. The state Office of Mental Health (OMH) oversees the facility.

amNewYork reached out to OMH regarding why Aherne had been discharged from the Manhattan Psychiatric Center, and is awaiting a response.

Prosecutors said Aherne arrived at Macy’s Herald Square and allegedly walked into the seventh-floor women’s restroom just before 3:15 p.m. on Dec. 11.

Thursday’s stabbing of a young mom inside a Macy’s Herald Square store bathroom shattered the normal joy of the holiday season at the historic department store.REUTERS/Eduardo Munoz

Authorities said Aherne allegedly confessed to traveling to Macy’s Herald Square location and buying a knife there. She allegedly then went on the hunt for someone to kill, motivated by what she said were voices in her head to murder someone before she herself was murdered.

According to information provided by the Manhattan District Attorney’s office, the victim, a 38-year-old woman from California visiting New York City, was in the process of changing her baby’s diaper when Aherne allegedly went on the attack.

The suspect allegedly produced a knife and stabbed the 38-year-old woman multiple times. In the process, the victim’s baby fell off the changing table onto the floor.

Prosecutors said the wounded victim, who suffered a laceration to her left arm, managed to subdue Aherne, who was then held by Macy’s store security until cops from the Midtown South Precinct arrived to make the arrest.

The victim was treated at a local hospital for her injuries. Her baby suffered redness and swelling from the fall, prosecutors said.

Aherne, meanwhile, allegedly told police that she could no longer tolerate treatment at mental hospitals and preferred instead to be incarcerated in prison.

At her arraignment, Judge Kacie Lally ordered Aherne remanded to the Department of Correction custody without bail. She is due back in court for a follow-up hearing on Dec. 17, and faces up to 25 years behind bars if convicted of the attempted murder charge.