A 13-year-old boy and his 12-year-old girlfriend will soon face capital murder charges in a Dallas-area double-shooting after the second victim died, authorities said Friday.

Alan Nevil, 48, died Thursday night from wounds he suffered in an Aug. 17 attack that also killed his wife, Darlene Nevil, 46, Garland police spokesman Joe Harn said.

Alan Nevil was found bleeding on a neighbor's front yard. He told police who shot him and authorities arrested the 13-year-old boy and 12-year-old girl within a quarter of a mile from the house, Harn said.

The children initially were charged with murder and aggravated assault in the shooting. Garland police said Friday in a statement they were working with the Dallas County District Attorney's office to upgrade those charges to capital murder.

For adults, the maximum sentence range is life in prison or death, in a capital murder case. But for juveniles, the maximum penalty is 40 years confinement in a Texas Youth Commission facility with a possible transfer to the Texas Department of Criminal Justice, said Durrand Hill, the head prosecutor in Dallas County's juvenile division.

At age 19, a juvenile could also be released from TYC on adult parole if they've been rehabilitated, he said.

"Homicide cases make up a very small percentage, less than 1 percent of the cases we prosecute in juvenile court," Hill said. "We're not seeking certification (as an adult) on this case, the law would not allow it."

A child must be at least 14 years old to stand trial as an adult, said Hill.

Hill said he anticipated that the upgraded capital murder charges against the youths would "happen very quickly," though he declined to speak in specifics about their case.

Police have declined to identify the children or reveal their relationship to the Nevils because they are minors.

They remain in custody at the Dallas County Juvenile Detention Center.

"They deserve everything they've got coming," said Juan Garcia Jr., the Nevils' neighbor and longtime friend. "Kids nowadays, they don't think twice."

Confident that Alan Nevil would awaken from his coma and fully recover, Garcia said he and his wife were just talking about how they could help him once he returned home when they learned that he had died.

"That was a shock," Garcia said Friday. "It was a real blow to everybody."

(This version corrects name of state agency to the Texas Department of Criminal Justice instead of the Texas Department of Corrections.)