The grieving mother had come to trust the two detectives, one a tall Anglo, the other a short Salvadoran. They asked how much she really wanted to hear.

“Lo quiero saber todo,” she said.

I want to know it all.

In the three years since she was told, Montgomery County prosecutors have secured eight first-degree murder convictions in the brutal killing of her son, 15-year-old Dennys Guzman-Saenz, making it one of the largest such cases in Maryland history. The final chapter is set for this month, when the last defendant is scheduled to be sentenced in Montgomery Circuit Court.

But for Dennys’s mother, Maxima Saenz-Sorto, the anguish has not waned. Her thoughts are dominated by grief over how Dennys lived and anger over how he died: Abducted from a Langley Park bus stop on a cold winter night, he was dragged into a blue Honda, wedged into the back-seat floor, beaten and taken into Montgomery. The attackers stabbed Dennys more than 50 times, first with a switchblade-type weapon and then a 14-inch hunting knife that pierced deep into his 130-pound body. When it was over — in a darkened park, 20 miles from Dennys’s home — they threw his body into a freezing creek.

“I would like to grab them and make them suffer just like my son suffered,” Saenz-Sorto said recently, speaking through a translator as she sat on her living room sofa. As she tried to describe the night Dennys disappeared, she gasped for air and slumped to her left side.

One daughter, Suleyma, steadied her. The other, Cindy, got a bottle of rubbing alcohol and held it under her mother’s nose — a routine that pulled her out of another fainting spell. “I really don’t know what to tell her,” Suleyma said. “It’s horrible.”

In many ways, it’s hard to imagine a more horrible crime — one that prosecutors, detectives and family members agreed to speak about in a series of interviews this summer. The following account also relies on court records.

Saenz-Sorto emigrated from El Salvador in 2000, leaving behind Dennys, Suleyma and Cindy. She worried about Dennys falling prey to Salvadoran gangs. “I thought he was going to be in danger there,” she said.

She saved enough money from her job cleaning apartments to bring them to live with her in Langley Park, in Prince George’s County just east of the Montgomery line. Dennys liked American shopping malls and video games, and he began to excel as a swift midfielder on a soccer team. But he was hardly away from gangs.

By late 2008, neighborhood members of Mara Salvatrucha, commonly known as MS-13, were actively recruiting Dennys, said Montgomery Detective Larry Haley. Dennys avoided parties where the gang members might be. He refused to join a planned attack on another gang, leading an MS-13 member to call him a sissy.

“He was getting pressure to join — and in that neighborhood, how could he not?” said Montgomery prosecutor Jeffrey Wennar. “But we found absolutely no information he ever did.”

Just after 7 p.m. on Jan. 18, 2009 — with no school the next day — Dennys walked from his family’s apartment to catch a bus to a friend’s house. He waited in the cold, finally calling Cindy to ask their cousin to pick him up and give him a ride. The cousin headed out to get him.

Earlier that day, in Germantown, local members of the 18th Street gang, an arch rival to MS-13, held a meeting. On the agenda was an upcoming call with a prisoner in El Salvador and possible punishment for a member who had violated gang rules by smoking crack, according to a witness in the case.

Afterward, five from the meeting got into Ysaud Flores’s Honda and drove toward Langley Park, where they began searching for MS-13 members. They followed one man, but he ducked into a building. They passed a slight Hispanic teenager alone at a bus stop and turned the car around. Two of them jumped out, punched Dennys in the groin and dragged him into the car.

Minutes later, back at the bus stop, Dennys’s cousin pulled up. But by then, the Honda was headed back to Germantown. One of its occupants called ahead to tell the others in Spanish that he was bringing a “present.” Others furiously punched Dennys, who had started to bleed. Where do you want to die? they asked. The song “Flowers for the Dead” blared over the speakers, said Jose Guzman, another detective on the case.

After arriving outside a Germantown apartment, a second group of 18th Street members climbed into a Toyota and the two cars headed south. Those inside the Honda kept asking Dennys if he was MS-13. “I am nothing,” Dennys said. “I am a Christian. I don’t want to die.”

One of the back-seat occupants, Silvia Martinez, 23, flipped open a butterfly knife and began stabbing Dennys. She bent back his index finger. Those in the car heard it snap and heard the teen again cry out in pain, according to prosecutors.

About 8:20 p.m., the cars pulled up to Malcolm King Park, just off Muddy Branch Road near Interstate 270. Two of the assailants dragged Dennys by his feet down a path to a creek. Others followed them. In all, eight people took turns beating, kicking and stabbing Dennys before heaving him into the creek. On the way home, several of them bought beer to celebrate, prosecutor Amy Bills said.

For three months, the killers remained free. Detectives interviewed dozens of people and chased false leads. Finally they got a tip: the nickname of an 18th Street gang member — “Yoni” — who had recently bragged about how he had “butchered” a kid and thrown him into a river in Gaithersburg. Detectives learned the names of some of Yoni’s confederates and began rounding up suspects. Some said nothing. Others laid out the story.

“There goes the gang loyalty, once the handcuffs go on,” Montgomery Circuit Judge Eric Johnson would later remark in a court hearing.

Eight defendants, including Flores, 33, Martinez, 23, and Joel Ventura-Quintanilla, 25, who also went by Yoni, have pleaded guilty to first-degree murder. Martinez, scheduled to be sentenced Aug. 14 in Montgomery, faces up to life in prison. All seven others have received lengthy prison sentences, and three other defendants pleaded to lesser charges.

Of the eight who admitted to murder, some had at least questionable immigration status, Wennar said, and face deportation if they ever get out of prison.

Dennys’s mother now knows everything that happened to her son.

These days, she is having trouble finding work. That only leaves more time to notice all the things that remind her of him: school buses, soccer fields, the smiling photos on her walls, the McDonald’s where Dennys would take a pocket full of coins to buy a chicken sandwich. She often walks through her apartment, quietly calling his name.