A Lloyd Harbor man has been accused of drowning his mother in their backyard pool on Wednesday.

Prosecutors say Denis Cullen Jr., 23, confessed to violently forcing his mother, Elizabeth Culeen, into their backyard pool and drowning her.

"He put her in a headllock, 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 Suffolk County Assistant District Attorney Robert Biancavilla. "He said she struggled violently, and he he was surprised that a woman of her stature could struggle as much as she did. He waited until she stopped moving, and then carried the body out of the pool and placed it next to a shed, and placed a dinghy covering the body."

Prosecutors say what provoked the murder was the 63-year-old poking her son with a finger while arguing with him to take his medication. 

They say that after Cullen murdered his mother, he stole money from her wallet, took her car keys and drove to the nearby Long Island Railroad station.

Cullen then allegedly met up with his sister and father in New York City. The three drove back to their Lloyd Harbor home where Cullen was arrested.

Cullen has been charged with second-degree murder and is being held on $5 million bail.

News 12 Long Island has learned that Cullen is the nephew of George Casey, Jr., the retired chief of staff for the U.S. Army during part of Operation Iraqi Freedom