The sheriff's office said Ralmond Winkler Jr. was fired on Aug. 19 after being indicted on nine charges. Deputies said he turned himself in Friday.
Deputies said they received information in May that Winkler could be involved in criminal activity and placed him on administrative leave in June.
DPS Texas Rangers division is confirming their independent investigation to ABC13.
Winkler faces seven charges related to child pornography, including "possessing or accessing visual material with a child under 18 engaging in sexual conduct."
Court documents also show Winkler is facing a charge for tampering with government records.
He's also accused of using his employment as a deputy with the Liberty County Sheriff's Office to "intend to obtain a benefit or harm or defraud another," according to court documents.
Texas Rangers said their investigation is still ongoing.