Sabbota said Hoffman had legal problems over drugs and had conflicts with his grandmother.

Watch: Teen's friends react to his death

Sabbota said his client fired her new .40-caliber semiautomatic handgun because she felt she had no choice.

Watch: Sources say woman bought gun after attack on Cipriano family in nearby Farmington Hills

"This is a 74-year-old lady who just bought a gun. It's not like she was a pro. I don't think she was in control of her emotions. She was afraid. She's not a big, strong woman," Sabbota said.

Regardless of what difficulties the teen gave his grandmother, there was no reason for her to shoot him, his father said.

"I'm not saying he was aggressive, but if he was, I don't understand how being aggressive but unarmed would justify her using deadly force," Michael Hoffman said.

Prior dispute at West Bloomfield home

Police were called to the home in March for a dispute between Layne and her grandson. According to police, Jonathan Hoffman was in the street screaming and was out of control. No charges were filed.

Jonathan Hoffman

Sandra Layne was charged with open murder on Monday after police say she shot and killed her 17-year-old grandson, Jonathan Hoffman, on Friday at her West Bloomfield Township home.

Sandra Layne mug

Sandra Layne was arrested Friday at her West Bloomfield Township home after her grandson called 911 to say he had been shot.

Teen’s connection to Tucker Cipriano

Hoffman and Tucker Cipriano, the man who is on trial for baseball bat beatings that killed his father and injured two other family members, were both students at North Farmington High School.

Local 4 has learned that the two may have been involved in an underground drug group at the school called the “K2 Crew.”

However, Hoffman’s father said the two weren’t close.

“I really don’t know anything about it, again. They weren’t friends as far as I knew. I think he knew him and that was about it,” said Michael Hoffman.