A 75-year-old woman has been sentenced to at least 22 years in prison for killing her teen grandson at their home in suburban Detroit.

Sandra Layne got a minimum sentence of 20 years for second-degree murder Thursday, along with a mandatory two-year prison sentence for using a gun to kill 17-year-old Jonathan Hoffman.

Hoffman was shot six times, including twice in the back, last year in West Bloomfield Township. Layne says she shot him out of desperation during a physical altercation, but a jury rejected her self-defense claim.

Prosecutors say there’s no evidence of Layne being injured by Hoffman. A recording of a 911 call shows Hoffman being shot again while pleading for help.

Layne told the court she was “sorry.” She’ll get credit for 11 months served in jail.