The teens had set out from their Sterling mosque last year for a pre-dawn meal, a common way to celebrate the Ramadan holiday. But what was supposed to be festive quickly turned to horror.

In the span of a few chaotic minutes, a driver approached the teens as they walked, an argument ensued, and suddenly the stranger was pursuing the teens with his car and then on foot with a baseball bat, a prosecutor told a Fairfax County courtroom Wednesday.

One of the teens heard a “thud and a metal ping” and glanced back to see the man standing over 17-year-old Nabra Hassanen, who was motionless on the ground, the prosecutor said.

It was the last time anyone saw Hassanen alive, but was hardly the end of her suffering.

Darwin Martinez Torres, 25, of Sterling, pleaded guilty to capital murder, rape and other counts Wednesday, as part of a deal with prosecutors that will allow him to avoid the death penalty in a case that generated national attention. Under the terms of the deal, he will be sentenced to life in prison when he appears before a judge again in March.

Fairfax County Commonwealth’s Attorney Raymond F. Morrogh said authorities still do not know a motive for the seemingly random attack, but they have found no evidence of what many feared: that Hassanen was targeted because of her Muslim faith.

Still, under an unusual aspect of the plea deal, Hassanen’s family will be allowed to question Martinez Torres about the crime. Mohmoud Hassanen, Nabra’s father, said he still believes his daughter was attacked because she was Muslim. The family plans to put the question to her killer.

“I remember her every day,” Mohmoud Hassanen said after the hearing. “I struggle with all my heart . . . Never is she going to come back to me.”

Joseph Flood, an attorney for Martinez Torres, said in an interview that his client is remorseful about what he did but that no bias was involved. Flood said evaluations have shown Martinez Torres has an IQ of 68 or less and is probably intellectually disabled. Flood said Martinez Torres is the one who proposed allowing the family to ask him about the murder.

“Throughout our representation, he has been deeply contrite,” Flood said. “At the time of arrest, he didn’t even know what it meant to be Muslim. He had never interacted with anyone Muslim.”

Prosecutors laid out the crime in chilling detail at Wednesday’s plea hearing. Chief Deputy Commonwealth’s Attorney Casey Lingan said the group of teens set out from the All Dulles Area Muslim Society mosque around 3:40 a.m. on June 18, 2017.

After eating at a McDonald’s, they were walking back to the mosque when Martinez Torres approached in a dark red car. Flood said his client had consumed 13 to 16 drinks that night and had smoked synthetic marijuana.

Martinez Torres pulled up behind a teen riding a bike and honked, sparking an argument, Lingan said. Martinez Torres drove at the teens, hitting the curb of Dranesville Road with a tire.

The teens ran up a hill to escape Martinez Torres, who drove up the hill after them, Lingan said. The teens ran into the parking lot of a bowling alley, and Martinez Torres drove back on the road and into the parking lot.

Martinez Torres then exited the car wielding a baseball bat, Lingan said. The teens scattered in fear, but Hassanen was at the back of the group, and Martinez Torres caught up to her. That’s when one of the teens heard the sickening thud and metallic ping, perhaps the sound of the bat striking Hassanen’s head.

When one of the teens glanced back, Hassanen was lying on the ground. Lingan said a friend of Hassanen’s saw Martinez Torres hit the bat on the palm of his hand and start walking in his or her direction.

The teens returned to the mosque and searches began for Hassanen, Lingan said. Officers were called, and at about 4:30 a.m. they arrived at the parking lot where the teens had encountered Martinez Torres. By then a large group of people from the mosque had gathered there.

Someone told officers they saw the vehicle of the attacker, and officers stopped it on the road, Lingan said. Martinez Torres was wearing no shirt or shoes, had scratches on his upper body and was covered in dirt and leaves, Lingan said.

There was a bloody handprint on a console of the car.

Officers found flip flops, broken eyeglasses and blood on a guardrail near where Hassanen disappeared. What happened would slowly be revealed as Martinez Torres was questioned at a nearby police station.

Lingan said Martinez Torres eventually told detectives that “everything went out of control” when he caught Hassanen while wielding the baseball bat. Lingan said Martinez Torres admitted hitting her on the head and then dragging her into the back seat of his car.

Martinez Torres drove Hassanen to a place near his Sterling apartment. She was unconscious but still alive, Martinez Torres told detectives. He removed her pants and sexually assaulted her, Lingan said. Martinez Torres flung Hassanen’s underwear into a tree.

Investigators found her naked body floating in a pond, Lingan said. A medical examiner would eventually determine that her skull was fractured and that her neck and one arm were broken.

The prosecutor’s recitation brought some of Hassanen’s friends to tears in the courtroom. Afterward, Fairfax County Circuit Court Judge Randy L. Bellows asked Martinez Torres to rise. The defendant stood in a green jail jumpsuit flanked by his attorneys and sheriff’s deputies.

“Do you agree that what Mr. Lingan said is in fact true?” Bellows asked.

Martinez Torres answered simply in clipped Spanish: “Sí.”

Martinez Torres, who is originally from El Salvador, is suspected of being in the country illegally, federal immigration officials said. They have placed a detainer on him, meaning they might pursue deportation proceedings against him in the unlikely event he is released.

The case has drawn an outpouring of emotion. Hassanen’s death prompted hundreds to turn out to remember her during a candlelight vigil in Reston, as well as other cities including Philadelphia and San Francisco.

During a preliminary hearing in October 2017, about 250 of Hassanen’s friends and relatives attended. The hearing was temporarily delayed after her father yelled, “You killed my daughter!” and lunged toward Martinez Torres. The girl’s mother also threw a shoe in the suspect’s direction.

In recent months, Martinez Torres’s attorneys had been readying a defense that he is intellectually disabled and therefore barred from facing the death penalty. Morrogh, the prosecutor, said Martinez Torres’s mental capacity would have been “hotly litigated” if the case had gone to trial and may have prevented him from facing that punishment.

Martinez Torres’s attorneys had been gathering evidence to make the case that he was exposed to mercury and other neurotoxins in utero and as a child growing up near a gold mine in rural El Salvador, stunting his brain development. Flood said Martinez Torres also had damage to the part of the brain involved with impulse control.

In the end, there may never be an answer for why he killed Hassanen, Flood said.

“Because of his impairment, he has limited insight into what precipitated [the crime],” Flood said.

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