Officials say the 43-year-old was discharged Thursday morning, then went to the Herald Square flagship where a mother was attacked in a restroom.
NEW YORK — The woman accused of stabbing a tourist as she changed her baby’s diaper at Macy’s Herald Square purchased a knife inside the store shortly before the attack and had been released from a psychiatric hospital earlier that day, prosecutors said at a Friday night arraignment.
The sequence adds urgency to questions confronting police, hospital administrators and the courts as the holiday crush fills Manhattan’s busiest retail blocks. Authorities identified the suspect as Kerri Aherne, 43, of Tewksbury, Massachusetts. The victim, a 38-year-old mother visiting from Southern California, was treated for stab wounds to her back and arm and is recovering. Her 10-month-old daughter was not injured. The case is in its early stages, with detectives building a minute-by-minute timeline based on store receipts, surveillance footage and interviews.
According to prosecutors, Aherne entered the seventh-floor women’s restroom just before 3 p.m. Thursday and stabbed the victim from behind. The victim’s partner helped restrain the attacker until store security took custody. Police recovered a knife and collected blood samples for testing. In statements summarized in court, prosecutors said Aherne told investigators she acted because “voices in her head” told her to kill or be killed. She faces counts of attempted murder, assault, weapon possession and child endangerment.
Officials said Aherne had a long psychiatric history and had been living at Manhattan Psychiatric Center on Randall’s Island for more than a year before being discharged Thursday morning. Investigators are reviewing her movements between the hospital and the store and have requested records related to her discharge and prior treatment. Authorities in Massachusetts have provided background on previous cases there, which New York prosecutors are weighing as they evaluate risk and potential preventive orders while the case proceeds.
The attack hit during peak shopping hours at the iconic department store, drawing a rapid response from uniformed officers stationed nearby and emergency medical workers called to the seventh floor. Macy’s said it was cooperating with the investigation and expressed sympathy for the family. Police said extra patrols were assigned to the building and nearby intersections through the weekend as foot traffic surged for window displays and holiday events in Midtown.
In court, prosecutors asked that Aherne be held without bail, citing the seriousness of the allegations and the danger to the public. A judge agreed and remanded her to city custody. Detectives plan to present additional evidence to a grand jury, including surveillance clips and interviews with restroom witnesses, early next week. The next hearing is expected in the coming days as prosecutors finalize the initial charging documents and seek more records from the hospital.
By Saturday, sections of the seventh floor near the restroom corridor remained restricted while investigators finished measurements. Shoppers moved around clusters of officers and store staff. A maintenance worker described a swift cleanup after forensic teams completed their work, and a cashier said customers were asking whether restrooms on other floors were open. The victim’s relatives were back at their hotel, officials said, and were expected to leave the city after medical follow-ups.
The suspect remains remanded pending grand jury review, and police said updates on the evidentiary timeline will be released after additional witness interviews scheduled early next week.
Author note: Last updated December 14, 2025.