Do you think a homicide detective would be any better than a normal man at killing?
He “should” be. In general, cops make poor criminals. In their day-to-day work, they operate under almost total government protection. They can do and say what they like. Thus, while they get practice with “actions”, the action is only 1% of what’s needed.
The other 99% is getting away with it, and intel. Cops and soldiers are not accustomed to that level of paranoia and protection. They almost always crack to routine investigative techniques, which they themselves use every day. I’ve seen it now many times.
I found a case where a det tried to kill his wife.
If he was looking at this one, he’d know almost immediately who did it. The det had a mistress and took out life insurance on his wife, before her suicide.
Criminals aren’t stupid. The pucker factor involved in acting without state permission is enormous. Criminals feel many times the adrenaline that a cop or soldier does.
It really messes with the ability to reason. When a person panics, they can only think with the old, reptilian portion of the brain. The impulse is to fight or flight, kill or run. Thinking is impossible under such circumstances; that’s where the “stupid” mistakes come in.