The accused gunman in a fatal Wisconsin school shooting was in court Tuesday.

Eric Hainstock is charged with killing his high school principal in Sauk County last fall.

Hainstock's defense team will argue that the 16-year-old defendant should be tried as a juvenile, not as an adult. Hainstock was 15 when principal John Klang was shot and killed at Weston High School last September.

The defense says Hainstock was a victim of abuse and deserves a chance at rehabilitation.

If he's tried as a juvenile and found delinquent, he could be released after turning 25. If convicted as an adult, he would receive a mandatory sentence of life in prison.

Eric’s grandmother, who once cared for him, took the stand and said Eric’s home life was difficult.

"Once they told me they had talked about it and he said 'I think you love the dogs more than you do Eric." "And what did Priscilla say?" "She said maybe I do” said Irene Hainstock.

Irene said she wished people knew the Eric she knows, and there was no indication that Eric had it out for Principal John Klang. But prosecutors say Hainstock knew what he was doing.