COEUR D'ALENE, Idaho (AP) — A neuropsychologist working in defense of a 16-year-old boy accused of killing his father and autistic brother says the teen didn't act deliberately.

The Coeur d'Alene Press reports that Craig Beaver testified Tuesday that Eldon Samuel III was highly emotional when he killed his 46-year-old father, Eldon Samuel Jr., and his 13-year-old brother, Jonathan Samuel, on March 24, 2014.

Beaver said Samuel was incapable of weighing the consequences of the kills and that he was in "survival mode." Samuel is accused of shooting his father and shooting, stabbing and hacking at Jonathan repeatedly with a machete.

Beaver, who reviewed case material including the call Samuel made to 911, said the elder Samuel had been outside shooting a gun due to fears about zombies before beating his son and prompting the attack.