BAKERSFIELD, Calif. (KGET) — A K-9 unit located 28 grams of concentrated cannabis oil and a cellphone last month believed to have been dropped on a prison yard by a drone, according to a court filing.

A confidential informant said an inmate coordinated drops at Wasco State Prison with someone on the outside and that heroin and methamphetamine had also entered the prison using that method, according to a warrant filed by prison investigators.

“The drone delivers the contraband behind central kitchen and central kitchen workers recover the contraband and smuggle the contraband into Facility ‘A'” then give it to the inmate, the informant said according to the warrant. Only inmates — not staff — have been linked to smuggling the contraband.