In Shiner, Texas, there’s little doubt among residents that a 23-year-old man who reportedly killed a man he found molesting his 5-year-old daughter in a horse barn should be hailed as a hero, not denounced as a criminal.

Yet some legal experts question why the father hasn’t yet been arrested and charged with murder, saying vigilante justice, no matter how the circumstances come about, can’t be tolerated in a civil society.

A Texas grand jury will have to deal with those questions next week as it takes a deeper look at the circumstances of the killing, and whether the father was justified in hitting the man so hard with his fists that he died.

In most jurisdictions, according to “Criminal Law,” a widely used textbook, the use of fists in defense if there are no other weapons present is automatically an example of reasonable force. But in this case, were emotions an extenuating circumstance that caused the angry dad to go too far? More broadly, when is a person in a defensive fight required to stop?

“Assuming it’s true that this guy was molesting the daughter … he would then have the right to defend her and hit him enough to have him stop,” James Harrington, director of the Texas Civil Rights Project, told Foxnews.com. “But you cannot summarily execute him, even though I can understand the anger he would have.”

He added: “The question is: When does it move beyond self-defense?”

And there’s another quirk to the case, suggests radio talk show host Geraldo Rivera, a lawyer.

“If he had a weapon and he used it to stop a sexual assault, he would not be indicted, but, ironically, the fact that he didn’t have a weapon leaves him more legally vulnerable than otherwise he would be,” Mr. Rivera told Bill O’Reilly Friday on Fox News. “In this case, you grab him off, now you’ve stopped the sexual assault, but now what are you doing? At what point does prevention of the sex assault become revenge, the implementation of vigilante justice?”

So far, the court of public opinion has stood steadfastly behind the father.

“Any father would have done that," Michael James Veit, a neighbor, told CNN on Thursday. "Everybody is saying the father is justified."

The killing happened last Saturday, according to Lacava County Sheriff Micah Harmon, after the man’s daughter had gone to a barn to feed the family’s chickens, and then began screaming.

When the father ran to investigate, he found a man described as a family acquaintance, a horse groomer, sexually abusing the girl. Police have not released any names, in part to protect the girl’s identity, and, in the case of the man who was killed, because they have not yet located his relatives in Mexico.

According to the county coroner, the man died of blunt force trauma to the head and neck. Eyewitnesses arrived to see the alleged molester already on the ground, not moving. The girl was taken to a hospital, where she was treated and released for minor injuries.

While police continue to investigate, they have so far found no reason to disbelieve the man’s story. The dad “had remorse,” says Sheriff Harmon. “It wasn’t his intent [to kill anybody]. He was protecting his daughter and doing what he thought he had to do to protect his daughter.”

Despite the dad’s potential legal liability, Rivera said, most American jurors – given the facts as known at the moment – would agree with Harmon.