Then in 2017, D.C. homicide detectives said, they learned that Melendez-Alvarado had been targeted in an elaborate revenge plot allegedly carried about by 34-year-old Oscar Ramos.

On Monday, after a two-week trial in D.C. Superior Court, Ramos was convicted of first-degree murder while armed in Melendez-Alvarado’s slaying. Prosecutor Michael Liebman said Ramos had come to the United States from El Salvador on a mission: to take revenge on Melendez-Alvarado for allegedly killing Ramos’s father years ago.

On the interstate that morning on May 28, 2015, police said, a driver pulled alongside Melendez-Alvarado’s vehicle and opened fire, killing him.

Authorities say detectives flew to El Salvador and investigated Ramos’s assertions but found no evidence that Melendez-Alvarado had been involved in the slaying of Ramos’s father.

Prosecutors told jurors that Ramos bragged about avenging his father’s death and killing Melendez-Alvarado. He posted about it on social media and boasted to others. During trial, prosecutors displayed Ramos’s social media posts and called witnesses to the stand who testified that Ramos had told them that he killed Melendez-Alvarado.

Prosecutors said Ramos, who relocated from El Salvador and lived in various homes in Maryland, Virginia and Massachusetts, created a fake Facebook account posing as a Latina woman and flirted with Melendez-Alvardo to find out his whereabouts.

Liebman told the jury that Ramos “used this account to lure Mr. Ramos to his death.”

Rachel E. McCoy and Camille Wagner, Ramos’s attorneys, argued that their client was innocent and that police had arrested the wrong person. They told jurors there was no direct evidence, including no witnesses, security camera video or DNA.

Ramos’s attorneys were successful in ensuring that jurors were not made aware that Ramos was affiliated with the MS-13 gang. Judge Maribeth Raffinan agreed that because prosecutors said the motive had nothing to do with the gang, evidence of Ramos’s affiliation would be prejudicial.

Ramos is scheduled to be sentenced on July 12.