I honestly don't know how to kill people, but there's something that seems strange to me.

1. The killing of Paulie: leave the gun, take the cannoli. I'd rather leave the cannoli and take the gun, since this is evidence. They also leave the car behind. Who's car is it anyway?

2. The killing of Sollozo and McClusky. Michael has to drop the gun, as Clemenza told him. Again: evidence...

As we see Vito in action in GFII, after he killed Fanuci, he smashed the gun in 100 pieces and spreads those. No evidence at all, and he can go home and eat spaghetti in peace...

Can someone explain this?