FORT WORTH (CBSDFW.COM/AP) — Authorities say a North Texas man charged with molesting children attending parties at a miniature-train complex he built in his yard has died after he was attacked while in custody.

The Fort Worth Star-Telegram reports another inmate at the Tarrant County Jail complex was suspected in Wednesday’s death of 76-year-old Clinton Don Simpson of Keller. Sheriff’s spokesman David McClelland says Texas Rangers would investigate.

READ MORE: Truck Loses Control, Slams Into Royse City Police Officer Michael Baley While Helping Stranded Motorist 

Clinton Don Simpson of Keller (photo credit: CBS 11 News)

A medical examiner reports Simpson suffered blunt force head injuries and died at a Fort Worth hospital. Manner of death was homicide.

READ MORE: Customs Officers Seize Narcotics At Texas-Mexico Border Worth $1.8M+ Hidden In Tires, Ice Chests

Simpson ran “Mr. Don’s Whistle Stop.” He was arrested in 2007 and faced more than a dozen charges of aggravated sexual assault, indecency with a child or sexual abuse.

MORE NEWS: Man Wanted In Dallas For Child Sexual Assault Charges, Jose Gerardo Ibarra Arrested At U.S.-Mexico Border

Records show Simpson was repeatedly found incompetent to stand trial and spent time at state hospitals.