Sandra Layne is convicted For Shooting her Grandson Six times

Sandra Layne is convicted of second-degree murder after she shot her grandson six times in their Michigan home last year.

A 75-year-old woman who shot dead her teenage grandson in Michigan has been described as a "monster" by her own grandson

Sandra Layne was found guilty on Tuesday of second-degree murder in death of 17-year-old Jonathan Hoffman at the home they shared in West Bloomfield Township last May

Jurors rejected her claim that she was acting in self-defence during an argument.

The boy's parents said the verdict was "vindication" for their son, whose actions and lifestyle were called into question throughout the trial.

"It's really hard to comprehend that your own mother could do something like this to your own child.

Layne fired 10 rounds at her grandson, who was living with her while his parents went through a divorce.

He was struck six times in the chest, abdomen and arm

She portrayed herself in court as a big-hearted grandmother who felt overwhelmed when Jonathan Hoffman was briefly hospitalised and then put on probation for drug use a year ago.

"I wanted him to pay attention to me. He had to listen. It wasn't a conversation. It was arguing. Swearing," a tearful Layne told the jury in testimony last week, explaining why she took out the gun.

During the trial prosecutors played a 911 emergency recording from last May that featured Jonathan Hoffman pleading for help and saying his grandmother had shot him.

She then shot him again while the operator listened on the other end of the line.

The call was crucial to the jury's decision.

"They said they played it over and over and over again" in the jury room, prosecutor Paul Walton said.

Michael Hoffman said his son showed "amazing courage" in his final moments of life.

Without the 911 call, he said, "we could have had a very different result" at trial.

Layne wept quietly as the verdict was read.

As she was being led out of court, her wrists handcuffed to a chain around her waist, some family members sitting with her 87-year-old husband, Fred, waved in a show of support.

Defence lawyer Jerome Sabbota said Layne was "devastated" by the verdict and is sorrowful over her grandson's death.