How did this guy not get charged with 2nd degree manslaughter?

This is another one where me and the readers will go separate ways.  How did the jury find this guy not guilty of 2nd degree manslaughter?  He went full retard.  Breathing hard, screaming into the radio.  But the kicker is his partner/cover. They did nothing but hop backwards.

That's significant.

That's his cover and he saw nothing alarming.  He was in a relaxed state and wasn't at the ready.

This guy was murdered and justice was not done.