Some things that worked against Jerome's self defense argument:
The kid on the floor was unarmed. His accomplice was, and the first shots were legal. Hard to argue your "he was still a threat". But yeah, he didn't know he wasn't armed, so that's not huge, but a factor.
Forensic evidence indicates the kid never moved after hitting the floor. Head wounds tend to bleed profusely. It was pooled where he fell, and the Pathologist said he didn't move when shot again, tending to indicate he wasn't conscience.
Most people who are conscience tend to react to a gun being pointed at them, and fired from what GSR evidence said was 18-24 inches from the kid's chest. The bullet wounds were tightly grouped. The Human Nature I know says you don't walk up within 2 feet of something you feel is a threat.
He tried to tell police the robbers fired. Not a big deal in and of itself, but they found no evidence, ie spent casings, bullet holes. Ersland's own personal physician and friend testified against him, claiming he tried several times to get her to change his medical records to reflect a bullet wound. They needed not fire on him to allow him to fire at them, but he got caught lying. Months after the robbery he tried to pass off a .22 shell casing as being found under a book rack in the store.
He apparently lied about his military record, trying to bolster his "I knew what I was doing, I was clear headed" defense....said he'd been in combat in the desert, but his military record said different.
Jurors said they were satisfied the prosecution proved the kid wasn't moving when he was shot again 5 times. They didn't rely on just the video.
Human nature that I'm familiar with nets you a conviction under such circumstances. I'm certain I could read "human nature" enough to seat 12 jurors and get a conviction on those facts.
And GarMan, what the fuck makes you and kind of expert on human nature or behavioral psychology?