The Lloyd Harbor man charged with second-degree murder in the drowning of his mother in the family pool last month was rushed to Stony Brook University Hospital early Sunday with self-inflicted wounds, Suffolk jail officials said.

Denis D. Cullen Jr., 23, who pleaded not guilty Tuesday to an indictment charging him with the Aug. 17 killing of Elizabeth Cullen, 63, was taken to the hospital after an attempt to harm himself, said Michael Sharkey, chief of staff at the Suffolk County Sheriff’s Department.

“He went to the hospital very early in the morning based on an incident where he attempted to hurt himself in his cell,” Sharkey said, adding that he was not able to characterize the incident as a suicide attempt.

“I don’t know if I’m going to call it that because I am not aware of the seriousness at this point,” he said.

Cullen is charged with drowning his mother after the two argued over whether he was taking his medication, prosecutors said.

He not only drowned his mother, but also choked her and likely beat her, a Suffolk prosecutor said in court Tuesday.

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Assistant District Attorney Robert Biancavilla said during arraignment proceedings before Suffolk County Court Judge Stephen Braslow that Cullen admitted to police that he wrestled his mother into a headlock and dragged her from the shallow end to the deep end of the pool as she struggled in vain to release his grip.

Cullen also pleaded not guilty at his first arraignment Aug. 18.

His attorney, John Halverson of Patchogue, who was assigned the case last week, could not be reached for comment.