Texas Rangers investigate leak of Adrian Peterson police file Montgomery County DA and HPD officialssay it was acquired by a Houston CBS station

This photo provided by the Montgomery County sheriffâs office shows the booking photo of Adrian Peterson. Peterson was indicted in Texas for using a branch to spank one of his sons and the Minnesota Vikings promptly benched him for their game Sunday, Sept. 14, 2014 against the New England Patriots. (AP Photo/Montgomery County sheriffâs office) less This photo provided by the Montgomery County sheriffâs office shows the booking photo of Adrian Peterson. Peterson was indicted in Texas for using a branch to spank one of his sons and the Minnesota ... more Photo: HOPD Photo: HOPD Image 1 of / 18 Caption Close Texas Rangers investigate leak of Adrian Peterson police file 1 / 18 Back to Gallery

Texas police have launched a criminal investigation into the leaking to the media of the police file on allegations that Minnesota Vikings running back Adrian Peterson recklessly caused bodily injury to his 4-year-old son when punishing him.

The Texas Rangers confirmed this week that they are investigating the illegal leak after receiving a request late Friday from Montgomery County District Attorney Brett Ligon and Houston Police Department officials. Tom Vinger, spokesman for the Texas Department of Public Safety, said all findings of the investigation will be reported to Ligon's office.

Text messages between Peterson and the boy's mother, as well as photos that purportedly show the child's cuts and bruises, have fueled public debate on the legal boundaries of corporal punishment since what appears to be the complete police case file was obtained Friday by Sports Radio 610, a CBS radio station in Houston. Peterson has acknowledged hitting his son on the backside with a switch, explaining that it was no different from the punishment he received as a boy.

Police and prosecutors say making that information public is itself a crime.

"It is a violation of the law regarding the confidentiality of child abuse investigations," said Phil Grant, the first assistant district attorney in Montgomery County.

He said that if it's found someone from Montgomery County released the information, he or she will be fired, but he said he feels certain the leak did not originate from there.

Houston police initially investigated the abuse report before determining that it did not happen within the city limits, but officials there denied news reports that it came from their department. The case was later transferred to Montgomery County, where the alleged child abuse is said to have occurred and where Peterson owns a $5 million home.

HPD spokesman John Cannon said city police did not take any photos as part of their investigation, so those released to the media were not from his department. He said Saturday he did not know whether the photos, which media reports say were taken by the child's doctor, were added to the case file while in HPD custody or after it had been transferred.

Deputy on grand jury

Texas child protective services officials say their investigations into child abuse ultimately result in civil cases, although they do comply with police requests for assistance in cases being considered for criminal prosecution. By Texas law, however, they cannot confirm whether they have an investigation ongoing or who has been investigated beyond what is revealed in courts, or in some circumstances earlier if a child has died.

The Chronicle reported Tuesday that Peterson, 29, was indicted Thursday by a grand jury led by the head deputy for the Montgomery County Clerk, renewing questions about Texas' grand jury selection system. The indictment of the NFL's 2012 MVP on child abuse charges sparked a media firestorm and represented another hit to the NFL, already battling media scrutiny for its initially tepid response to a domestic violent incident involving the Baltimore Ravens' Ray Rice.

On Friday night, Peterson chartered a private plane to Houston and drove to the Montgomery County jail, where he was booked about 1 a.m. Saturday and quickly released on $15,000 bond. The Vikings deactivated Peterson for last Sunday's game, a lopsided loss to the New England Patriots, but he was reinstated Monday after three days on the bench.

Peterson issued a written statement on Monday saying that he never imagined he would be in the position where the world would be judging his parenting skills and calling him a child abuser.

"I voluntarily appeared before the grand jury several weeks ago to answer any and all questions," he stated. "I was interviewed by two different police agencies without an attorney. In each of these interviews, I have said the same thing. … that I never ever intended to harm my son."

'Cause for concern'

Corporal punishment is legal in Texas and non-deadly force against a child by a parent or guardian is permissible. But the punishment is abusive if it causes injury. A blow that leaves a bruise, welt or swelling, or requires medical attention, could be judged abusive. The guidelines also say use of an instrument "is cause for concern."

Prosecutors have said what Peterson did was "unreasonable."

Peterson faces up to two years in prison and a $10,000 fine if convicted. He also could face a minimum six-game suspension from the NFL under a recently toughened domestic violence policy.

The Vikings' decision to allow Peterson to rejoin the team on the field Sunday is also generating controversy. One sponsor suspended its relationship with the team and some stores have pulled Peterson merchandise from their shelves. The team's move also drew criticism from Minnesota's Democratic governor, Mark Dayton.

"It is an awful situation," Dayton said Tuesday. "Yes, Mr. Peterson is entitled to due process and should be 'innocent until proven guilty.' However, he is a public figure; and his actions, as described, are a public embarrassment to the Vikings organization and the State of Minnesota. Whipping a child to the extent of visible wounds, as has been alleged, should not be tolerated in our state. Therefore, I believe the team should suspend Mr. Peterson, until the accusations of child abuse have been resolved by the criminal justice system."

Chronicle reporters Cindy Horswell and Mihir Zaveri and the Associated Press contributed to this report.