Jose Alejandro Lopez-Torres (Courtesy of U.S. Attorney’s Office)

A jury on Monday convicted six MS-13 gang members in connection with three brutal murders and an attempted murder in Northern Virginia, delivering an across-the-board verdict in a sweeping federal case against the violent street gang.

After less than two full days of deliberations, jurors found that the gang members played various roles in the stabbing and dismembering of two men, the fatal shooting of another, and a failed plot to kill a fellow gang member.

The verdict is a victory for prosecutors, who initially charged 13 people, all of them members of a clique known as the Park View Locos Salvatruchas, under a law once used to fight the Mafia. Six defendants pleaded guilty before trial and testified against the others. One defendant is being tried separately.

“Extreme violence is the hallmark of MS-13, and these horrific crimes represent exactly what the gang stands for,” U.S. Attorney Dana J. Boente of the Eastern District of Virginia said in a statement.

Shotgun and machete. (Courtesy of U.S. Attorney’s Office)

The defendants, all in their early- to late-20s and dressed in light-colored button-up shirts, stood silently as a clerk read the verdict for each charge. A female family member of one defendant, Jesus Alejandro Chavez, sobbed loudly and yelled at prosecutors in Spanish as the clerk said he’d been found guilty of shooting and killing an Alexandria man in June 2014. Chavez and other defendants bowed their heads.

Sentencing will take place over the summer. All defendants face mandatory life imprisonment.

“We’re extremely disappointed with the result, but the fight is not over,” said Christopher Amolsch, an attorney for Christian Lemus Cerna, who was convicted of taking part in one of the stabbings. “We plan to use every means necessary to keep going.”

The case dates back to October 2013, when prosecutors said several of the defendants plotted to kill a member believed to be cooperating with police.

Authorities intercepted them in Woodbridge one night as they were driving to Gar-Field High School, where the member, known only as Peligroso, took night classes. They found two machetes and a sawed-off shotgun in their car.

A week later, gang members killed Nelson Omar Quintanilla Trujillo, who was suspected of alerting police to the failed murder plot, prosecutors said. After luring Trujillo into Holmes Run Park in Fairfax County, they stabbed him to death, dismembered him and buried him in the woods. Several months later, they stabbed and decapitated Gerson Adoni Martinez Aguilar, an MS-13 recruit who was accused of stealing gang money and having sex with an incarcerated member’s girlfriend. They buried him in the same park.

The third murder took place in June 2014, when Chavez and two other gang members shot and killed Julio Urrutia in Alexandria, mistaking him for a rival gang member, according to the prosecutors.

Omar Castillo (Courtesy of U.S. Attorney’s Office)

The trial stretched seven weeks in the U.S. District Court for the Eastern District of Alexandria. A jury of 11 men and one woman heard testimony from more than 40 witnesses, including gang experts, law enforcement agents and former gang members. As a precaution, the court installed extra security measures during the proceedings. U.S. District Judge Gerald Bruce Lee, the presiding judge, called it “an epic and complex case for this court.”

Prosecutors presented no forensic evidence connecting the defendants to the crimes. Instead, they built the case almost entirely on testimony from cooperating defendants and a confidential FBI informant who secretly recorded hundreds of phone calls with the gang over the course of a year.

The informant, a 33-year-old El Salvadoran immigrant known as Junior, was a leader of a local MS-13 clique called the Silvas Locos Salvatrucha. He has worked with the FBI for more than a decade, receiving $42,000 over the years for providing information about the gang. In late 2013, after learning about the murder of Trujillo, Junior agreed to use an FBI cellphone and body wires to record conversations with the defendants.

The Washington Post is withholding Junior’s real name at the request of prosecutors, who said the witness could be in danger.

Prosecutors presented numerous recordings they said include gang members taking credit for the killings. According to transcripts prepared by the FBI, gang members repeatedly told Junior the gory details about how they stabbed and dismembered the victims, and buried them in shallow graves.

A turning point in the investigation came when Junior persuaded one of the defendants to show him the grave sites in Holmes Run Park, where the gang buried Trujillo and Aguilar. During the trip, Junior wore a video wire, recording the entire meeting. The FBI later excavated the two bodies.

Assistant U.S. Attorney Julia Martinez praised Junior in closing arguments, saying he risked his life to help solve the murders.

“Junior, I submit to you, is a hero,” Martinez told the jury.

But defense attorneys contended that Junior was little more than an opportunist who manipulated both the gang and authorities. They said Junior was motivated to work with prosecutors by the promise of money and immigration benefits.

Frank Salvato, an attorney for Cerna, said Junior concealed his own brushes with the law, including a robbery and beating he allegedly took part in.

“He’s a habitual manipulator and liar,” Salvato said. “He is no hero.”

Others argued that the defendants were merely falsely bragging to a senior gang member when they talked with Junior about their roles in the slayings. Defense attorneys said Junior maintained the appearance of an MS-13 member for years by lying about committing crimes.

“Junior is living proof that anyone can make it through MS-13 on false bluster alone,” said Jeffrey Zimmerman, an attorney for Alvin Gaitan Benitez, who was convicted of helping murder Aguilar and reburying Trujillo’s body.

The court also heard testimony from several gang members who accepted plea deals. One of them, Jose Del Cid, 20, admitted to taking part in every killing in the case. While on the stand, he also told jurors that he had killed at least two people when he was a teenager in El Salvador.

Defense attorneys repeatedly challenged the credibility of Del Cid and the other cooperators, saying they were pinning blame on their counterparts in hopes of getting reduced sentences and other benefits from the government.

Martinez said although the cooperators were “no choir boys,” they were the only people present for the killings who could implicate the other defendants.

“If they lie, they get no sentence reduction. Telling the truth now is their best incentive,” Martinez said. “What else would you have us do?”

Jose Lopez Torres, Omar Dejesus Castillo and Manuel Paiz Guevara were also among the defendants convicted Monday.

MS-13 has operated in the Washington region since the early 1990s and has between 2,000 and 3,000 members in the area, according to gang experts.

An aggressive crackdown by the FBI and local police in the mid-2000s drove the gang underground for several years. But more recently, law enforcement experts say, MS-13 leaders in El Salvador have pressured cliques in the Washington region to rebuild. The effort has unleashed a new round of violence in the past three years, experts said.