GRAND RAPIDS, Mich. (AP) — Jury deliberations will start in western Michigan in the murder trial of a 13-year-old boy who fatally stabbed a younger boy at a playground.

Lawyers gave final arguments Thursday in Kent County court after experts gave different opinions on the teen’s state of mind last summer when he killed 9-year-old Michael Connor Verkerke.

The jury returns Friday. The key issue is whether the teen is criminally responsible. He was 12 at the time.

Priya Roa says a childhood of abuse wrecked his mental health and put him in a “trance-like” state of rage. But Susan Tremonti, testifying for prosecutors, says the teen knew what he was doing, even hiding the knife in sand before the attack.

The Associated Press isn’t naming the boy who’s on trial because of his age.