ARLINGTON (CBSDFW.COM) – A Tarrant County jury sentenced convicted killer Hector Acosta to the death penalty for the September 2017 murders of Erick Zelaya and 17-year-old Iris Chirinos in Arlington.

Acosta, a self-proclaimed sicario (“hitman”) for the Cartel Del Noreste shot his then-roommate Zelaya and his girlfriend Chirinos in their sleep, before mutilating their bodies with a machete and two-by-four. He decapitated Zelaya, and after dumping the bodies in a shallow grave in his backyard, he rode a bicycle through the neighborhood to a walking trail a few blocks away where he left Zelaya’s head along with a sign threatening future violence. Acosta claimed to have killed the couple in retaliation for a past drive-by incident in which he believed Zelaya had been a participant.

READ MORE: Texas Secretary Of State's Office Announces Full Forensic Audit Of 2020 General Election in Four Texas Counties

During the punishment phase of the trial, the prosecution introduced evidence of another capital murder Acosta was believed to have committed in a Fort Worth house. In July 2017, Acosta and accomplices bound and viciously beat Triston Algiene while robbing him. After Algiene gave them the wrong PIN number for his bank account, he was shot to death. Acosta then cut his body in half, buried him under the house and covered his body with cement. Arlington Police Detective Grant Gildon received information about this murder and informed Fort Worth Police, who discovered the body after digging up the concrete slab. The hard work of Gildon, fellow Arlington PD Detective Michael Barakat and Fort Worth Police Detectives Jerry Cedillo and Ernie Pate was instrumental in bringing Acosta to justice.

“Have you ever knowingly in your life sat in the room with a more dangerous person?” lead prosecutor Kevin Rousseau asked the jury in closing arguments for the punishment phase. “He can’t follow the rules of a cartel, but you are expected to believe he’ll follow the rules of a prison warden? He is extraordinarily violent. He deals in terror. It’s his job.”

READ MORE: Feds Make New Recommendations To Texas To Prevent Deadly Power Outages From Happening Again

A native of Monterrey, Mexico, Acosta allegedly showed an interest in gang life from as early as age 7. He participated in multiple gangs in both Mexico and Houston before joining the Cartel Del Noreste for which he claimed to have performed kidnappings, tortures and other murders. Evidence was presented that while being held in the jail awaiting trial, Acosta attempted to start a drug trafficking operation.

“Acosta is not a product of a bad environment,” said prosecutor Tim Rodgers. “He is the bad element in his environment. That’s what he is and what he wants to be.”

Jurors deliberated for just over four hours before sentencing Acosta to the death penalty.

MORE NEWS: Sunnyvale Credits 'Small-Town Values' For Incredible Vaccination Rate

“Some people can get better. Some are just bad,” said Rodgers.