WELCH, W.Va. (AP) — Eleven suspects have been arrested in an investigation into illegal drugs allegedly delivered by drones into a federal prison in southern West Virginia. Another man under investigation who fled officers was later found dead, authorities said.

McDowell County Sheriff James Muncy said his office was contacted in November by officials at the medium-security Federal Correctional Institution, McDowell in Welch to help with increased drone use in the area. In December, the sheriff’s office started receiving multiple tips about drone deliveries.

Muncy said in a statement Friday the arrests were made from mid-December through early February. The charges included introduction or attempts to introduce contraband into a correctional facility, possession with intent to deliver a controlled substance, unlawfully operating a drone, terroristic acts and felony conspiracy.

Muncy didn’t say what drugs were allegedly flown into the facility or whether any of those arrested are inmates there.

A Louisville, Kentucky, man wanted on an outstanding warrant in the investigation fled officers on foot Feb. 9. Members of the sheriff’s office found him dead on Feb. 15. The statement didn’t indicate where he was found, and his body was sent to the state medical examiner for an autopsy.

One of the arrested suspects is a juvenile, Muncy said. In addition, two suspects were charged with assault and battery on an officer and fleeing on foot. Another suspect in the case was charged with being a fugitive from Pennsylvania.

Most of the suspects remained held Monday at the Southwestern Regional Jail in Holden. Jail records didn’t indicate whether they have attorneys who could comment on the charges.