The singer made at least four trips to the pharmacy in the days leading up to his death.

In the final years of his life, Prince developed a severe addiction to the drug Percocet, TMZ reports.

The publication, who broke the news of the singer’s death last week, cite multiple sources connected with Prince’s family who say the singer became addicted after being prescribed the painkiller in 2009 when he was suffering from hip problems. Prince underwent hip surgery in 2010, but was allegedly already using the drug regularly.

Percocet has an infamously high risk for dependence and can be extremely deadly when taken in high doses or mixed with alcohol.

Rumors have circulated that the emergency plane landing and hospital trip the week before the singer’s death was the result of a Percocet overdose. TMZ says the FBI is currently investigating who wrote Prince’s prescriptions as well as who filled them. He was seen making multiple trips to the pharmacy in his final days.

Earlier today, the singer’s lawyer acknowledged Prince was on pain medication, but dismissed any speculation about addiction.

“People use medication. The question is, are you on meds in a dangerous way?” he said.