An inmate serving a 20-year sentence for manufacturing marijuana died in custody Wednesday morning.

According to the Crossroads Correctional Center, Donald Gilligan, 50 died of apparent natural causes at 1:40 a.m. Wednesday.

Gilligan was serving a 20-year sentence for manufacture/produce or attempt to manufacture/produce less than five grams of marijuana in residence w/child or within 2,000 feet of school, college, school bus; keeping or maintaining a public nuisance; possession of a controlled substance except 35 grams or less of marijuana; unlawful use of drug paraphernalia –amphetamine/methamphetamine from Putnam County.

Gilligan was was received in the Missouri Department of Corrections on Aug. 23, 2012.