(CBS/AP) MINNEAPOLIS - Byron Smith, a Minnesota man accused of killing two teenagers who broke into his home last year, has been charged with first-degree murder.
A grand jury indicted Smith under seal Wednesday on two counts of first-degree murder with premeditation. The new charges were announced Thursday.
The 64-year-old Smith initially was charged with two counts of second-degree murder in the Thanksgiving day 2012 deaths of 17-year-old Nick Brady and 18-year-old Haile Kifer.
In Minnesota, a first-degree murder charge must be issued by grand jury indictment.
If convicted, Smith faces a mandatory penalty of life in prison without parole.
Prosecutors say Smith shot the teens multiple times and left their bodies in his Little Falls house for a day before authorities were notified.
One of Smith's attorneys, Adam Johnson, says Smith was acting in self-defense.