The Lloyd Harbor man charged with drowning his mother in the family’s swimming pool this month has been indicted and is scheduled to be arraigned Tuesday on a second-degree murder charge, officials said.

Denis D. Cullen Jr., 23, of White Hill Road is being held on $5 million cash bail in connection with the Aug. 17 killing of Elizabeth Cullen, 63, according to a news release from Suffolk District Attorney Thomas Spota. Cullen’s attorney could not be reached for comment.

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A grand jury handed up the indictment Wednesday, according to court records.

Cullen, who prosecutors said killed his mother after the two argued about whether he was taking his medication, will appear before Suffolk County Court Judge Stephen Braslow in Riverhead.

During Cullen’s arraignment after his arrest, prosecutors said he had “confessed” to putting his mother in a headlock and dragging her from the shallow end of the pool to the deep end as she struggled to loosen his grip.

Police said they were called to the home to do a wellness check and discovered Cullen’s body about 4 p.m. and that Denis Cullen surrendered at 6:50 p.m.