PARIS (AP) – France’s justice minister says investigators believe that drones seen months ago buzzing above a prison may be linked to the brazen escape of a notorious French criminal.

Justice Minister Nicole Belloubet said authorities are urgently looking for gaps in the security system that would have allowed heavily armed men to land a helicopter in the prison yard and fly away with Redoine Faid, whose brother was visiting him.

The helicopter was found torched in a field. French media reported that the three men took the pilot hostage and later freed him. Faid’s brother has been detained.

A wanted notice says Faid is believed to have made his escape in a utility company truck.

French prime minister Edouard Philippe said 2,900 officers are searching for Faid.