John H. Spooner was convicted last week of first-degree intentional homicide. He acknowledged shooting the 13-year-old in the chest last year while the teen's mother watched.
At a sentencing hearing Monday, Judge Jeffrey Wagner denied Spooner the possibility of parole.
Darius' mother, Patricia Larry, says justice was served when the jury rejected Spooner's insanity plea. She still has a pending wrongful-death lawsuit against the shooter.
Some of Spooner's shotguns were stolen in a break-in at his home two days before he killed Darius. Spooner told the jury he suspected the teen in the theft. Police said they searched Darius' home and didn't find the weapons.
The shooting was captured on a security camera video and was entered into evidence during the trial.