Maria Reyes holds a dress her daughter Damaris was going to wear for a Sweet 15 Quinceanera celebration. Damaris went missing Dec. 10 and was later found slain. (Dan Morse/The Washington Post)

Venus. Romero. Iraheta.

The young MS-13 associate listed her full name before plunging the knife into the 15-year-old girl, so Damaris A. Reyes Rivas would know who killed her, an FBI agent testified Thursday. Iraheta, 17, blamed the Gaithersburg teen for the killing of her boyfriend just a week earlier and wanted revenge.

“[Venus] told the victim she would never forgive her and would see her in hell,” FBI Special Agent Fernando Uribe said.

The chilling testimony came Thursday before a judge in Fairfax County juvenile court certified Iraheta to be tried as an adult in the brutal killing of Damaris. The preliminary hearing and two others offered fresh details about intertwined MS-13-related killings that have resulted in the arrests of 18 teens and young adults across the Washington area and underscored the resurgence of the region’s biggest and most violent gang.

The hearings came as federal officials announced a nationwide anti-gang crackdown had resulted in more than 1,300 arrests.

Fifteen-year-old Damaris A. Reyes Rivas of Gaithersburg, right, with her mother, Maria Reyes. Rivas’s body was discovered by Fairfax police near an industrial park in the Springfield area. (Family photo)

At the heart of the cases, Uribe testified, was a love triangle of sorts. Iraheta and Damaris both had relationships with 21-year-old Christian Sosa Rivas, who authorities say was killed by MS-13 associates along the Potomac River in Dumfries around New Year’s Eve. A search warrant states Sosa Rivas was targeted by MS-13 leaders because he was claiming to be a leader of the gang. Iraheta blamed Damaris for helping lure Sosa Rivas to the spot where he was killed.

Iraheta, of the Alexandria section of Fairfax County, and other MS-13 associates’ revenge plot would play out Jan. 8, according to testimony. Jose Castillo Rivas, 18, who is also charged with Damaris’s killing and had a preliminary hearing Thursday, told Uribe he had gone out to buy cigarettes and was confronted by a handful of MS-13 associates. The associates told Rivas he had to set up a meeting with Damaris or they would hurt his young child, Uribe testified.

Rivas called Damaris, who had run away from home in December and became involved with the gang, and picked her up in Annandale. A person familiar with the prosecution’s case had previously said Damaris thought she was going to smoke marijuana.

Rivas drove them to Springfield’s Lake Accotink Park, where they met up with another group. Uribe testified that Iraheta told him she began to beat Damaris and question her about what happened to Sosa Rivas and the nature of their relationship. Uribe testified that Rivas also told him that he kicked Damaris in the head.

Damaris admitted that she had a sexual relationship with Sosa Rivas, Uribe testified, and told the group to call another MS-13 member to get more details about Sosa Rivas’s killing.

It was a frigid day, but the group of about 10 young people, between the ages of 15 and 21, forced Damaris to remove her shoes and shirt and stand in the snow, Uribe testified. They thought it would help with the interrogation, but there was another reason as well.

(Claritza Jimenez/The Washington Post)

“She was forced to remove her shirt to make her feel pain like Christian,” Uribe testified.

Iraheta and the group then took Damaris to a wooded area a short distance from the park, near where one of the juveniles charged in the case lived. Iraheta, who Uribe testified had grown up in a neighborhood in El Salvador controlled by MS-13, confronted Damaris for the final time along with a handful of MS-13 associates charged in her murder. Damaris was beaten again.

Iraheta stabbed Damaris’s abdomen and neck 13 times as she lay on the ground, according to testimony. She also allegedly sliced a diamond tattoo off Damaris that the teen had gotten as a reminder of Sosa Rivas, a person familiar with the case said.

A search warrant in the case states that her attackers took videos of Damaris’s dying moments, and one was so brazen that he was wearing a court-ordered GPS monitoring bracelet from a previous offense. Wilmer A. Sanchez-Serrano, 21, who also had a preliminary hearing Thursday, plunged a large sharpened stick into Damaris’s neck at one point, Uribe testified.

A total of 10 people have been charged in connection with Damaris’s killing, including five with murder. The other defendants waived their preliminary hearings or had them continued until later dates Thursday.

During her preliminary hearing, Iraheta listened stoically as Uribe recounted the vicious attack. Iraheta’s mother cried softly, with her face pointed toward the vaulted roof of the courtroom at one point. Damaris’s mother sat a short distance away, dabbing away tears.

Attorneys for the defendants and Damaris’s family declined to comment after the hearing, but Damaris’s mother, Maria Reyes, told The Washington Post in March that she thought her daughter was escaping gang violence when she brought her here from El Salvador.

“I didn’t know people like that existed in the United States,” Reyes said of MS-13. “I thought it was super safe to have my daughter here with me.”