A former Florida Keys firefighter was arrested for allegedly stealing fentanyl from an ambulance and falsifying public records, authorities said.

Brian Keith Burt, 45, was arrested Wednesday and faces charges of grand theft of a controlled substance and fraud, Monroe County Sheriff’s Office officials said.

Burt, of Key Largo, had been employed with Islamorada Fire Rescue as a firefighter/paramedic, officials said.

Earlier this month, officials with the fire department notified the sheriff’s office that Burt had obtained a partially used vial of fentanyl from an ambulance after a medical call, officials said.

He also is accused of forging another paramedic’s signature in documents related to the disposal of the drug, authorities said.

Other crew members noticed discrepancies in the documentation related to the drug’s use after the call and warrants were issued for Burt’s arrest.

He was booked into jail on Wednesday.