GAINESVILLE, Texas -- Two guards at a state juvenile prison are accused of choking a teenage inmate until he lost consciousness.

According to court documents released Friday, a third guard at the same facility punched another teenager in the head and body four times with a closed fist.

State troopers charged those three men, along with a former guard from another facility with official oppression this week. The arrests are the latest in an ongoing state investigation into the troubled Texas Juvenile Justice Department.

In December, Gov. Greg Abbott asked the Texas Rangers to investigate reports of sexual misconduct by state employees. The governor’s request followed an internal investigation by the Juvenile Justice Department.

Since last year, at least nine Texas juvenile correctional officers have been arrested on abuse or misconduct charges.