 COLD SPRING HARBOR, N.Y. (CBSNewYork) — A prosecutor said a man charged with second-degree murder in connection with the death of his mother put her in a headlock, dragged her into a pool and drowned her.  A man charged with killing his mother by drowning her in their Long Island swimming pool Wednesday gave details of the crime in a taped confession, prosecutors said.Denis Cullen Jr., 23, of Lloyd Harbor, is facing charges of second-degree murder in the death of 63-year-old Elizabeth Cullen at their home on White Hill Road.During Cullen's arraignment Thursday, prosecutors said he told police during a multi-hour confession that he and his mother were in the pool when they got into a fight about him not taking his psychiatric medication.He had been diagnosed several years ago with paranoid schizophrenia and had been recently released from the hospital. '"Cullen is being held on $8 million bail.Elizabeth Cullen ran Winn Collen Interiors out of Cold Spring Harbor. This is a son who killed his mother and the way he killed her, the way he describes how it was done, was chilling,” Assistant District Attorney Robert Biancavilla said. Biancavilla said they have a video confession in which Cullen admitted to fighting with his mother Wednesday morning after she scolded him for not taking his medication. "He put her in a headlock, walked from the shallow end of the pool with her in the headlock to the deep end of the pool -- all the time while she was struggling," said Robert Biancavilla with the Suffolk County District Attorney's Office.Cullen drowned her there, according to prosecutors, and then took her body out of the pool and put it near a shed in their backyard, covering it with a dingy. ""He said she struggled violently and he was very surprised that a woman of her stature could struggle as much as she did," Biancavilla said.Cullen's attorney said he spoke with with his client for about 20 minutes Thursday morning. “While we were processing the scene, the suspect returned to the home and we placed him under arrest,” Sini said. The victim was a daughter of famed Vietnam Maj. General George Casey and the sister of the U.S. Army commander of the same name. “There’s a lot of work to be done,” his defense attorney, Steve Fondulis, told WCBS 880’s Sophia Hall. “I have to determine if he has a psychiatric background, I have to determine if he’s under a doctor’s care and I have to look at the videotape.” 
 
 Cullen’s attorney says his client is not guilty.
– In what authorities describe as a "chilling" case, New York police say a 23-year-old put his mother in a headlock and drowned her in the family's pool on Long Island on Wednesday. Assistant DA Robert Biancavilla says 63-year-old Elizabeth Cullen initially argued with her son, Denis Cullen, in the shallow end of the pool over whether Denis had taken his psychiatric medication. But when she poked him, per the AP, Denis dragged her into the deep end, "waited until she stopped moving, and then carried the body out of the pool," Biancavilla tells CBS New York. Biancavilla says Denis tried to hide the body before stealing his mom's car, cash, and credit card. He then traveled to his sister's house where he reportedly confessed. Police were called to the scene and found Elizabeth Cullen dead in the backyard. Biancavilla adds that Denis—previously diagnosed with paranoid schizophrenia, per WABC—later confessed. "He said she struggled violently and he was surprised a woman of her stature could struggle as much as she did," says Biancavilla, calling the description "chilling." Denis, who is the nephew of former US Army Chief of Staff George Casey, is charged with second-degree murder.