Details of the agreement reached this week were not released, but police say the teen will serve at least 10 years behind bars because the charge was capital murder. He had been facing a maximum 40-year sentence and was set to go to trial Monday.
The Dallas County public defender's office, which is representing the boy, said it doesn't comment on matters pertaining to juvenile offenders. A call to a public defender in the juvenile division, who was listed as previously having represented the boy, was not immediately returned Friday.
Word of the plea bargain was first reported by The Dallas Morning News.
The boy and his then 12-year-old girlfriend were both charged in Aug. 17 shootings that killed 46-year-old Darlene Nevil at her home in Garland, Texas. Her husband, Alan Nevil, 48, was also shot, but made it to a neighbor's front yard and was able to call the police. He was able to tell the police who shot him before he died of his wounds Sept. 2.
Authorities also recovered the handgun they believe was used in the slayings.
The girl, now 13, is set to go on trial March 28. Her court-appointed, Irving, Texas-based attorney, Charles Martin Jr., declined to comment Friday.
A court official, who requested anonymity because the case involves minors, said the victims were related to the girl. The Associated Press will not report their exact relationship in an attempt to protect the identities of the minors charged in the crimes.
Both children were being held at the Dallas County Juvenile Detention Center because suspects must be at least 15 to be tried as adults.
Information from: The Dallas Morning News, http://www.dallasnews.com