PONTIAC, Mich. -

A 75-year-old Detroit-area woman has been sentenced to decades in prison for the fatal shooting of her teen grandson.

Sandra Layne was given 20-40 years in prison on a second-degree murder conviction.

Jonathan 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 claim of self-defense.

A 911 call reveals the 17-year-old being shot again while pleading for help. Prosecutors say Layne's guidelines call for a minimum of 12 years in prison for the murder, plus two years for the gun crime.

Before her sentencing Thursday, Layne addressed the court. Through tears, she said she cared deeply for her grandson and did everything she could to keep him happy. She said his parents never responded to her pleas to them to get him help once he started doing drugs.

"I know what I've done," Layne said. "There isn't a moment in my life I don't feel pain."

The teen's mother, Jennifer Hoffman, also spoke before the sentencing and called Layne "pure evil."

Previous stories: