(WPHL) – A Pennsylvania man was charged Monday with drugging and killing his own mother.

Sean Rivera, 28, of Falls Township in suburban Philadelphia, was arrested on allegations that he killed his 72-year-old mother, Carol J. Clark, by putting fentanyl in her iced tea, shooting her, and then leaving her body in a shed.

According to Bucks County District Attorney Matt Weintraub’s office, police on Sunday afternoon received a report of a verbal domestic dispute between two brothers over the whereabouts of their mother.

According to Weintraub, Rivera called his brother, Adam Clark-Valle, Sunday morning to let him know their mother had died after an illness. Clark-Valle, who lived in New York at the time, drove to Rivera’s home to mourn. When Clark-Valle arrived, he asked Rivera where their mother was, but Rivera did not give an answer.

Then, at one point, Rivera told his brother that their mother had had a heart attack and was in a local hospital, which Clark-Valle checked but found no record of her being there.

Clark-Valle called the police, and the Falls Township Police Department put out an alert, asking the public to help them find Clark.

During a search of Rivera’s home and vehicle, detectives found two guns, a Home Depot receipt, a padlock, an empty padlock package, and a set of bolt cutters.

According to police, on Saturday night, Rivera put “diluted fentanyl” in his mother’s iced tea. Between 2 a.m. and 3 a.m., while his mother was “in a conscious but lethargic state,” he put her in her own car and drove her to a shed in Philadelphia, police said.

Then he used bolt cutters to cut off the padlocks on the shed, took his mother inside, and shot her “approximately five times,” police said. He then closed the doors to the shed, locked them with the padlocks he had bought, and left, they said.

After Rivera was apprehended, police opened the shed with a key he still had on him.

Rivera was charged with criminal homicide, kidnapping to facilitate a felony, kidnaping to inflict terror or injury, aggravated assault, possession with intent to deliver a controlled substance, possession of an instrument of crime, possession of a weapon, false imprisonment, unlawful restraint, and recklessly endangering another person.

No potential motive was given.

Rivera was being held without bail at the Bucks County Correctional Facility.