A Collin County jury sentenced Raul Cortez to the death penalty in connection with one of the 2004 quadruple murders in McKinney.
The jury deliberated for seven hours on Monday during the sentencing phase.
The jury found the 28-year-old man guilty of capital murder Thursday in the shooting deaths 18-year-old Austin York. York was killed alongside 46-year-old Rosa Barbosa; her 25-year-old nephew, Matthew Barbosa; and his friends, York and 17-year-old Matthew Self.
All four were found dead inside Barbosa's home in McKinney.
Cortez's mother had to be led from the courtroom Monday morning after she got on her knees and begged a Collin County jury to spare her son's life, the Dallas Morning News reported. Sobbing was also heard from the courtroom as York's mother took the stand.
Cortez proclaimed his innocence throughout the trial.
Co-defendant, 26-year-old Eddie Ray Williams, testified that he and Cortez killed the four victims in a botched robbery plot.
A DNA expert linked Cortez to latex gloves and duct tape found at the crime scene, and a forensics analyst linked ammunition found in the victim's bodies to a .25-caliber bullet found lodged in Cortez's ceiling.
Williams, who is mentally disabled, is still facing his capital murder trial.
