Iowa Teen: I Thought I Killed Goblin, Not Brother Cody Metzker-Madsen of Iowa is pleading insanity in foster brother's death By Newser Editors and Wire Services Posted Nov 6, 2014 12:06 PM CST 32 comments Comments Cody Metzker-Madsen says he was lost in a fantasy when he attacked his foster brother with a brick last year. (KETV NewsWatch 7) (Newser) – An Iowa teenager has testified that when he killed his 5-year-old foster brother, he was in a fantasy world and thought he was killing a goblin. Cody Metzker-Madsen told the western Iowa jury yesterday that he visits a world only he can reach whenever he plays with someone. He says he didn't realize until afterward that what he thought was a goblin was actually his foster brother, Dominic Elkins. His lawyer is using an insanity defense. Authorities say Metzker-Madsen killed Dominic last year while the two were playing outside of their home near Logan. Metzker-Madsen was 17 at the time. The boy's body was found at the bottom of a ravine. An autopsy showed he died of blunt-force head injuries and drowning.