PLAINFIELD, Conn. (WTNH) — A five-month investigation into the overdose death of a man in Plainfield led to the arrests of two people, including his son, police said.

Dean Barr, 52, overdosed on Feb. 15 after his son, 28-year-old Justin Shirley of Griswold, gave him the heroin and fentanyl that killed him, according to Plainfield police.

Police arrested Shirley Tuesday and charged him with second-degree manslaughter and sale/distribution of illicit narcotics. Officers arrested 56-year-old Sally Williamson of Plainfield on Monday and charged her with cruelty to a person and providing a false statement.

Police said Williamson brought Barr to Shirley’s house, where Shirley gave him the drugs, then took Barr back to his house, where he showed signs of overdosing on narcotics.

Williamson allegedly left Barr unattended in a parking lot on Putnam Road and did not call help or render aid, despite the 22-degree weather and heavy winds.

Shirley remains behind bars on a $50,000 bond. He was due in court Wednesday. Williamson was released on a $25,000 bond and is due in court on Aug. 1.

Anyone with additional information is asked to call the Plainfield Police Department at (860) 564-0804. Callers can remain anonymous.