Why didn't Sonny kill the hostages?

Question

In Dog Day Afternoon with Al Pacino from 1975 I am wondering, when the cops showed up Sonny just made it look like a publicity stunt instead of someone who actually means business.

To me it didn't make any sense. If the police knew that he was'nt willing to use violence, then they would have taken advantage of that. The fact that he is an armed bank robber requires possible killings of police and hostages if things go wrong. And if the cops truly believed about a dozen young women were about to be murdered on live television they probably would have been a lot more likely to give into his demands instead of double crossing him. Also, the police ended up killing his friend Sal in cold blood, without even giving him a chance.

Why didn't Sonny just start killing hostages instead of compromising and playing games with the police and releasing them one after another?

Answer 1

On the one hand, Sonny did state that if the police didn't cooperate, bodies would start flying out the door.

However, later on in the movie, while Sonny did look non-violent, he made himself out to be the only one who could control Sal, who he portrayed as a cold-blooded killer - e.g. if anything happened to him while he was out talking to the police, Sal would start killing hostages.

Actually, Sal was as averse to killing as Sonny, as he privately questioned his "bodies flying out the door" comment.

Alas, the fiction wound up getting Sal killed as the police then believed him to be a dangerous murderer.