RIVERHEAD - A Lloyd Harbor man accused of drowning his mother has pleaded not guilty.

Denis Cullen Jr. was arraigned on a grand jury charge of second-degree murder Tuesday morning.

As News 12 has reported, the 23-year-old allegedly dragged his mother Elizabeth into their backyard pool early this month.

Officials say Cullen put her in a headlock underwater until she stopped moving.

Investigators say the pair had been arguing about Cullen not taking his medication.