I wrote about this on facebook a few days ago when this happened. In my opinion the father acted justly, with out a deadly weapon or intent to kill the man. He was defending someone who could not defend themselves.

The incident was slightly different than the op but the the sherrif said the following: (taken from CNN)

Asked whether they would press charges against the father, the sheriff responded, "You have a right to defend your daughter. He acted in defense of his third person. Once the investigation is completed we will submit it to the district attorney who then submits it to the grand jury, who will decide if they will indict him."

Harmon described the dad as "very remorseful," adding that he didn't know the man was going to die.

Authorities were withholding the deceased man's name while they notified next of kin. Officials did not know immediately if he has a prior criminal history.