By DEANNA BOYD
dboyd@star-telegram.com
This report contains graphic descriptions of violence.
FORT WORTH -- When the Arlington father caught his teenage stepson sexually assaulting his 8-year-old daughter late Jan. 2, investigators say the 32-year-old man did the right thing -- he called police.
The 18-year-old was arrested by Arlington police on suspicion of aggravated sexual assault. The girl was taken to the hospital, where an examination revealed she'd been raped anally. And the father issued a stern warning to his wife.

"He didn't want anybody to help (the teen)," said Sgt. Cheryl Johnson, supervisor of the Fort Worth sex crimes unit, adding that the man also stated that he would hurt his stepson.
But unbeknownst to the father, police say, the man's wife posted bond for her son's release from the Arlington jail. When the teen called home for a ride on the early afternoon of Jan. 3, it was his stepfather who answered the phone and arrived at the jail to pick up the teen.

But the pair didn't go home, investigators say.
Instead, the Arlington man drove his stepson to an abandoned house in east Fort Worth where he delivered his own brand of justice. He severely beat the teen with a baseball bat, then anally raped him with a wrench-like metal tool.
On Friday, the father turned himself into the Tarrant County Jail on a warrant for aggravated sexual assault. He was released Saturday after posting a $17,500 bond.
"This is a very unique case, but we have a criminal justice system in place, and no one can take the law into their own hands," Johnson said. "They need to allow the criminal justice system to work for them and although the process may seem long, it is the process that works."

The Star-Telegram and Star-Telegram.com are not naming the father or the teen to protect the identity of the 8-year-old girl.
Johnson said after the sexual assault, the father left the scene. The stepson made his way to a pay phone, where he called police and was hospitalized.
That same day, investigators obtained a search warrant for the abandoned house in the 2700 block of Canberra Court near Cobb Park. Though boarded up, the pair made entry inside through a board that moved, Johnson said.

"We did find evidence at the scene to corroborate our victim's story," Johnson said.
Tarrant County court records show the father had received two years deferred adjudication probation in November 1996 after pleading guilty to burglary of a habitation.

As part of that plea-in-bar agreement, the man avoided prosecution on four other charges: possession of marijuana, theft by check, and two cases of assault with bodily injury. His probation, however, was revoked in 2000, and he was sentenced to two years in prison.
The father also received a 30-day jail sentence for assault with bodily injury in 2001 and a 20-day jail sentence for possession of marijuana in 2006, records show. The 18-year-old stepson does not have an adult criminal record in Tarrant County, records show.