Reginald Newkirk, 54, died Sunday morning at Kings County Hospital after a medical emergency while in NYPD custody in East Flatbush, police said. He is at least the sixth person to die this year after falling ill in NYPD custody.

Police said Newkirk, a Brooklyn resident, was arrested Friday on a charge of criminal possession of a controlled substance. He was taken to a hospital for medical attention after the arrest and cleared. At about 2:10 p.m. Saturday, officers requested emergency services for him, and he was taken to Kings County Hospital, where he died Sunday.

The NYPD’s Force Investigation Division is investigating. It was not immediately clear whether Newkirk was awaiting arraignment on the possession charge.

Three others who died after being held in NYPD custody earlier this year were found by the city medical examiner to have died accidentally, with acute drug intoxication listed among the causes. Deaths in NYPD custody before arraignment do not receive the public Board of Correction reviews that follow deaths at Rikers Island.