A Texas sheriff’s deputy charged with sexually assaulting a 4-year-old girl and accused of threatening her immigrant mother with deportation if she reported him was found dead in his jail cell, apparently of suicide, the authorities said on Tuesday.

The man, Jose S. Nunez, was found in his cell at Karnes County Correctional Center at 5:45 p.m. on Monday, said Sgt. Elizabeth Gonzalez, a spokeswoman for the Bexar County Sheriff’s Office. She said the Karnes County Sheriff’s Office and the Texas Ranger Division were investigating.

Sergeant Gonzalez said Mr. Nunez had been held at the jail since June 17.

Mr. Nunez, 47, was arrested that day in Bexar County after the girl’s mother said that her child made an “outcry” about the abuse, and she reported him to a fire station, Sheriff Javier Salazar said at a news conference that month.

Mr. Nunez was charged with super aggravated sexual assault of a child, a first-degree felony because of the girl’s age, Sheriff Salazar said. In the event of a conviction, the charge carries a prison sentence of at least 25 years.