Christopher Millwater’s family lost him at a familiar Long Island waterfront, where prosecutors say a confrontation with his ex-girlfriend and her boyfriend turned fatal.
STONY BROOK, N.Y. — Christopher Millwater was killed near a Stony Brook waterfront his sister described as his favorite place to fish; nine months later, both people originally charged with murdering him have pleaded guilty to manslaughter and are awaiting sentencing.
Millwater, 52, of Selden, died Nov. 10, 2025, after Suffolk County police found him gravely injured outside 21 Shore Road near the Stony Brook Yacht Club. He was taken to Stony Brook University Hospital, where he was pronounced dead. A funeral home obituary lists his birth date as Dec. 8, 1972. Reporting after the homicide also said he had recently shared encouraging news about a battle with cancer. Against that personal backdrop, the criminal case that followed centered on Millwater’s former girlfriend, Kacy Corso, and her then-boyfriend, Victor Panebianco.
Corso, now 34, pleaded guilty July 22 to first-degree manslaughter and hindering prosecution. Panebianco, 32, followed on Aug. 11 with his own plea to first-degree manslaughter. The pleas mean the two will not stand trial on the second-degree murder charges announced after a Suffolk County grand jury indictment in December. They now face separate September sentencing hearings: Corso on Sept. 2 and Panebianco on Sept. 22. Corso is expected to receive seven years in prison, while Panebianco is expected to receive 25 years to life.
Those different expected sentences reflect a case in which prosecutors attributed different conduct to the two defendants. Corso acknowledged at her plea hearing that she intended to cause serious physical injury to Millwater but reportedly said there had been no plan to kill him. Her attorney, Christopher Gioe, said afterward that she had accepted responsibility and maintained that her role in the events was limited. Corso also agreed to cooperate with prosecutors, according to reporting on the plea arrangement.
Panebianco’s alleged conduct was described more directly in the prosecution’s account of the fatal encounter. Authorities said surveillance video showed him chasing Millwater after an initial confrontation involving the defendants’ and victim’s vehicles. Prosecutors said Panebianco caught Millwater and stabbed him in the chest. They further alleged that he threatened Millwater, told him to stay away from Corso and kicked him after he was motionless. Panebianco’s August manslaughter plea removed the need for prosecutors to prove the original murder charge to a jury.
The confrontation began in a parking area used by people visiting the yacht club, marinas and other waterfront destinations. Prosecutors said Corso drove into the lot with Panebianco as her passenger. Millwater arrived shortly afterward and parked next to her. Corso then moved her car in front of Millwater’s, according to the state. When Panebianco approached, Millwater drove around Corso’s car in an effort to leave. Prosecutors said Corso drove into Millwater’s vehicle before he abandoned the car and ran.
The next portion of the encounter was captured on surveillance footage that became central to the indictment. Prosecutors said Panebianco pursued Millwater while swinging an object. During the attack that followed, Millwater could be heard asking, “You’re stabbing me?” and calling for help, according to authorities. He suffered fatal chest wounds. Prosecutors said Corso could also be heard yelling during the episode. Afterward, Panebianco returned to the vehicle and Corso drove away, the district attorney’s office alleged.
When police initially reported Millwater’s death, much of that sequence was not yet public. Officers said only that he had been found at about 3:40 a.m., had been the victim of violence and later died at the hospital. Homicide detectives appealed to the public for information. Corso was arrested Nov. 20 and charged with second-degree murder. Panebianco was detained in North Carolina, where authorities worked with Suffolk County investigators before his return to New York. Prosecutors later described both defendants as residents of King, North Carolina.
The district attorney’s December announcement turned the investigation into a detailed criminal accusation. Suffolk County prosecutors said phone evidence, surveillance footage and witness information supported the charges. District Attorney Raymond A. Tierney said at the time that the indictment reflected the office’s effort to seek justice for victims of violent crime. Because an indictment is an accusation rather than proof, both defendants remained presumed innocent of the murder charges until their later guilty pleas resolved the cases on manslaughter counts.
One detail that attracted wide attention involved social media. Fox News reported that Millwater had “liked” a Facebook post from an account in Corso’s name only days before his death. The account also contained older material indicating that Corso and Millwater knew each other. The fact that Millwater was Corso’s former boyfriend gave the online interaction obvious narrative interest, but the verified material reviewed does not establish that the Facebook “like” was the motive for the killing. Prosecutors’ public descriptions have focused primarily on the defendants’ conduct at the marina and the evidence documenting it.
Millwater’s connection to the waterfront offers a different perspective on why the location matters. His sister told News 12 that Stony Brook had been his favorite place to fish. Fox News described the yacht club parking area as a place better known for boating access and waterfront activities than violent crime. A social media post attributed to Millwater shortly before his death indicated that he had received favorable news following cancer treatment. His obituary later listed visitation and a prayer service in Selden, where he had lived.
In court, Corso’s plea produced one of the clearest public statements about her claimed intent. State Supreme Court Justice Timothy P. Mazzei asked about the plan behind the encounter. Corso responded, “There was no plan.” She nevertheless admitted the manslaughter count and acknowledged intending serious physical injury, according to courtroom reporting. The distinction allowed the case against her to end without a trial over whether the evidence established the mental state required for the original murder accusation.
Panebianco’s plea three weeks later brought the same finality to the remaining prosecution. Tierney said after Panebianco admitted manslaughter that the guilty plea could not take away the pain experienced by Millwater’s friends and loved ones but would spare them a difficult trial. The district attorney also credited the Suffolk County Police Department and Stokes County Sheriff’s Office for their investigative work. Panebianco’s lawyer was identified in reporting as Jonathan Manley.
The case now approaches sentencing rather than fact-finding. Corso’s expected seven-year term has not yet been formally imposed, and Panebianco’s reported 25-years-to-life sentence likewise awaits the Sept. 22 hearing. Their guilty pleas, however, settle the central criminal liability question that remained open after Millwater’s death. For his family, the legal process is nearing an end in the same year that began with two murder defendants and the possibility of lengthy trials.
Author note: Last updated August 28, 2026.