A grandma feared her grandson, she testifies during the murder trial on the witness stand Wednesday.

Sandra Layne, 75-year-old charged with first-degree murder for fatally shooting her teenage grandson, Jonathan Hoffman at their suburban Detroit home. She told jurors how he kicked her in the abdomen and demanded money and a car to leave Michigan.

Layne described herself as an overwhelmed grandmother that "adored" the 17-year-old grandson who she took care of after his parents divorced and moved to Arizona.

"Did you want to kill this young man?" defense attorney Jerome Sabbota asked.

"Of course not. I still love him," Layne replied, crying and looking distraught in the witness stand.

Autopsy revealed Hoffman was shot three times in the chest and revealed the teen had traces of synthetic marijuana in his body.

Layne standing in her defense described the hours that led up to the shooting. She said Hoffman tested positive for a drug test and was at risk of being sent to jail for violating probation in a marijuana case. He then demanded $2,000 and the keys to her car.

"I went into my bedroom and started looking for the gun," Layne said. "I wanted him to pay attention to me. He had to listen. It wasn't a conversation. It was arguing. Swearing."

She said Hoffman kicked her and struck her in the head. "I shot the gun," Layne said.

Layne's lawyer said she was in fear of her life because of Hoffman's erratic behavior and his use of synthetic marijuana.

Prosecutors asked Layne during cross-examinations why she simply didn't kick him out of her house if she was so afraid of him. She shared that he never struck her before.

"Instead of sending Jonathan home and telling his parents to pick him up or calling his Aunt Judy, the option you choose is to buy a gun," assistant prosecutor Kelli Megyesi said.

In her testimony, she cried recalling a trip to a hospital where Hoffman was being treated for drug use which was a "tipping point."

"I knew he was troubled, but I didn't realize he was that troubled," she said.

Cross-examination will resume Thursday. Layne faces life in prison without parole if convicted.