Inset left: Kacy Corso (Suffolk County Sheriff's Office). Inset right: Christopher Millwater (Selfie/Facebook). Background: The marina of the Stony Brook Yacht Club where the fatal stabbing occurred in Long Island, N.Y. (Google Maps).
A woman in New York state is facing substantial prison time after admitting to the role she played in a man's stabbing death at a yacht club and marina on Long Island's north shore.
Earlier this week, Kacy Corso, 34, pleaded guilty to charges of manslaughter and hindering prosecution over the November 2025 stabbing death of 52-year-old Christopher Millwater.
In December 2025, Corso and her then-boyfriend, Victor Panebianco, 32, were indicted on charges of murder in the second degree over the slaying. Millwater was Corso's ex-boyfriend.
Now, prosecutors are likely to push for a seven-year sentence for Corso because she agreed to fully cooperate with the state's case against Panebianco, according to a courtroom report by Newsday.
"She accepted responsibility," defense attorney Christopher Gioe said outside the courtroom building in Riverhead on Wednesday. "She had a very limited role in what happened in this case."
The incident occurred on Nov. 10, 2025, at the Stony Brook Yacht Club. Corso claims she simply drove the car that day.
During her plea hearing, she reportedly said it was only her intent to "cause serious physical injury" to her ex-boyfriend.
"What was the plan?" state Supreme Court Justice Timothy Mazzei asked Corso at one point in the proceedings.
In low tones, the woman replied: "There was no plan."
Plan or not, Millwater was stabbed to death outside 21 Shore Road during the early morning hours, police said.
"Shortly after Corso drove into the parking lot at the yacht club, Millwater pulled in and parked next to her," prosecutors wrote in a press release announcing the indictment. "After Corso then positioned her car in front of Millwater's car, Panebianco allegedly exited the passenger side of Corso's car and approached Millwater's car. Millwater drove around Corso's car, and towards the exit of the parking lot. Corso then allegedly drove her car into his vehicle. After the crash, Millwater exited his car and ran from the scene."
Next, the state alleges Panebianco chased after the victim, swinging some sort of object, citing surveillance footage.
"You're stabbing me?" the frightened man asked his killer as he was knifed through his heart and lungs, authorities said.
"Video then shows Panebianco caught up to Millwater, and while Millwater was on the ground, Panebianco allegedly threatened to kill him and yelled at him to stay away from Corso," the press release goes on. "Corso can also be heard yelling at Millwater. As Millwater lay motionless on the ground, Panebianco allegedly kicked Millwater in the head. Panebianco then got back into Corso's car and she drove off."
Police found Millwater at around 3:40 a.m. and rushed him to Stony Brook University Hospital where he was pronounced dead.
The victim had "liked" one of Corso's Facebook posts in the days before the murder, Fox News reported at the time of the indictment.
Panebianco is still charged with murder in the case and faces up to 25 years in prison. Corso is slated to be sentenced in September.