Already separated from his wife, Patricia, O'Mara kicked his way into what had been the couple's marital home, Hillsborough County sheriff's deputies said. He fought with his wife while his two children called 911.

O'Mara, 38, wasn't prosecuted for that outburst because he didn't have a history of violence, prosecutors said.

O'Mara shot and killed his children and himself Friday night, less than a week before his first child support payment was due.

Deputies say he gunned down Sean, 12, and Lauren, 13, and also shot and critically wounded his ex-wife. Patricia Parra-Perez remained in the intensive care unit of St. Joseph's Hospital on Monday.

The omen that the crumbling 15-year marriage was about to turn violent surfaced Oct. 21, five days before the divorce was settled. That's when deputies responded to a domestic violence call from the O'Mara marital home in Lutz.

``He kicked in the garage door - the interior door - set the alarm off and kicked in a bedroom door and grabbed her,'' said sheriff's Lt. Rod Reder. ``The kids dialed 911.''

O'Mara was gone by the time deputies arrived, Reder said. Deputies forwarded the case to the Hillsborough State Attorney's Office, where prosecutors declined to pursue criminal charges.

Assistant State Attorney Pam Bondi said her office gets more than 10,000 requests for prosecution in domestic violence cases each year, and some don't warrant prosecution.

``There was no history of violence in the reports. There were no injuries,'' Bondi said. ``It appeared to be an isolated event.''

Parra-Perez was sent a letter from the victims' assistance program, asking her to call within seven days for advice on how to avoid becoming a domestic violence victim, Bondi said. The letter included a section on how to obtain an injunction for protection.

``We didn't hear from her,'' Bondi said.

Whether an injunction would have made a difference is anybody's guess.

Deputies said O'Mara went to his ex-wife's new town house on Le Clare Shores Drive with the intention of killing his family.

She was starting a new life without him. She had a new home and a new car and was back to using her maiden name.

When she pulled up Friday night, O'Mara approached her with a .38-caliber Taurus handgun and shot her once in the head.

He pursued Sean to the front door where a single shot took his life. O'Mara then spotted Lauren running down the street. He caught up to her and shot her as well, deputies said. Then, he turned the gun on himself.

Four shots were fired, all at close range. He had five more rounds in his pocket.

What set him off? Nobody's certain.

``We're still investigating,'' Reder said. ``I don't know if we will ever know.''

While friends said Parra-Perez was terrified of O'Mara, court records gave no indication the proceeding was anything but typical. All arrangements were agreed upon, including visitation and child support.

Their divorce settlement, filed in August, became official Oct. 26, having moved quickly through the courts.

O'Mara was granted visitation on every other weekend and on Wednesday nights, the divorce records said.

Child support agreed upon was $700 a month for each child, with the first payment due Wednesday. Whether O'Mara would have been capable of making that deadline remains a mystery. Last week, he quit his job as office manager of a mortgage company, a move friends described as uncharacteristic.

Monday, the community continued to mourn the loss of the couple's children.

Crisis counselors helped more than 100 students at Martinez Middle School, where Sean and Lauren attended classes.

The Hillsborough County School District brought in eight counselors. By midmorning, the district added five more to handle the crush of students, teachers, parents and one neighbor who needed counseling.

``It's always tragic to lose a teacher or a classmate or a staff member. A father is supposed to protect their children, not do them harm,'' said district spokesman Mark Hart.

Counselors met with students individually and in small groups. Students were encouraged to draw or write about their feelings, and they created wall-sized poster tributes.

Hart said some students were crying, but for others, the situation sparked questions of domestic violence and divorce. Students wondered if this could happen to them.

``What you see on the faces is more distress and not tears,'' he said. ``Rare is the case where the children are the murder victim. Rarer still is the father being the murderer, so it's grim.''

Reporter Elizabeth Lee Brown contributed to this report. Reporter Keith Morelli can be reached at (813) 865-1504.

Keyword: Multimedia, for an extensive list of online resources on domestic violence and abuse.