In the end, the hammer did not matter.

A juvenile court judge yesterday said it made no difference whether a Mt. Lebanon teenager beat his ex-girlfriend with his fists or a 2 1/2-pound hammer as the two high school students walked along a wooded trail Oct. 31, 2007.

Either way, Common Pleas Judge Kim Berkeley Clark said, 17-year-old Robertino DeAngelis inflicted serious injury on his victim, and the weapons he carted in his backpack that day, including a butcher knife, duct tape and a box cutter, showed he wanted to kill Sarah DeIuliis, 18.

In what she called the most difficult decision in her 10 years on the bench, Judge Clark found the defendant delinquent of attempted homicide, aggravated assault and unlawful restraint. She will tell him Oct. 6 what his punishment will be.

Immediately after the attack Mr. DeAngelis threw himself in front of a light rail train, causing grave injuries. Ms. DeIuliis suffered a fractured eye socket, a gash to her head and a concussion in the beating.

Mr. DeAngelis' attorney, Patrick Thomassey, had argued that if it couldn't be determined that his client used a hammer in the attack, he shouldn't be judged delinquent for attempted homicide.

Mr. DeAngelis, dressed in a dark suit, sky-blue dress shirt and tie, kept his elbow planted on the defense table and his face buried in his hand during yesterday's ruling and the victim-impact statements that followed.

After the judge ruled, Ms. DeIuliis stood, flanked by her parents, and spoke in a soft, shaky voice about living in fear that Mr. DeAngelis would attack her again.

"Your honor, more than anything, I want to be able to know that he won't come back. I want to be able to know that I do not need to be afraid," said Ms. DeIuliis, who began her freshman year this week at a college her family does not wish to disclose.

The defendant remains on an electronic monitoring program that confines him to his grandparents' house. Once, it set off an alarm -- due to a power outage -- that the victim said sent her into a panic.

As the defendant's health improves and he becomes more mobile, she told the court, she feared that the kind of person who is willing to run into a train by choice would have no qualms about harming her again.

Mr. Thomassey later told reporters his client was "a normal 17-year-old kid with normal goals and problems" and he would "bet his life" that "this will never happen again."

The judge said she was inclined to send Mr. DeAngelis to a secure facility such as the New Castle Youth Development Center, but delayed her decision until Oct. 6, so the defendant can undergo medical and psychiatric testing.

Also after the ruling, the young man's mother, Diana DeAngelis, told the judge that she was worried about whether her son's ongoing medical problems could be handled properly by whatever facility she chooses. She said his most serious injury was not sustained in the train accident but when he was being transported between facilities and medical personnel did not know his age. She said they intubated the then-16-year-old with a tube meant for an adult, causing stenosis, a condition in which his windpipe closes up.

The victim's father, Joseph DeIuliis, addressed the judge about the fact that even with the most strict detention in the juvenile system, the defendant will be released from juvenile court supervision at the age of 21.

"We've changed windows, doors and modified our home security system, but we're not sure when he'll be home."

During the three-day trial, the judge heard from 17 witnesses. She said high-profile experts such as former Allegheny County Coroner Cyril H. Wecht and the current medical examiner, Karl Williams, both of whom discussed a hammer's impact on a human skull, did not sway her.

Instead, she relied on the testimony of the victim since the defendant said he couldn't recall anything. The judge also took into account details from other witnesses about events surrounding the assault.

According to testimony, Mr. DeAngelis stated to a friend that he wanted to rape and kill the victim. He sent her a text message with what she interpreted as her date of death for a tombstone and another text with lyrics to a song called "Last Day on Earth."

The judge said she could have considered the duct tape and the box cutter as simply construction tools, but added, "I don't know any reason a person would walk with a butcher knife in their backpack, especially when they are going to and from school."

The defendant, the judge said, purposefully crushed the victim's cell phone during the beating. He then told his ex-girlfriend he wanted to kill himself on the T-tracks, a detail the girl reported to an off-duty police officer who happened onto the scene before the train accident occurred.

The judge said it was clear that "most of [the victim's] injuries, if any, were not caused by the hammer," but, "I believe he had the other items [in the backpack] there to do what he had threatened to do," and, "he intended to kill himself" afterward.

Dr. Wecht testified earlier this week that the victim's head wounds were not consistent with a hammer attack. Dr. Williams said the victim's head wound could have been caused by a glancing blow from a hammer.

Ultimately, the judge never determined whether the hammer was used. She found the defendant committed aggravated assault because Ms. DeIuliis suffered a concussion, and therefore a serious bodily injury to a vital organ.

She made no mention of it in court, but since she did not know whether there was a hammer, the judge dismissed a single count of aggravated assault with a deadly weapon.