Need help with Godfather 2

I'm trying to kill the first Capo in New York City, and it says ''Execute him with a pistol''. And every time I go up there, I shoot him in the head with the regular pistol and nothing happens. Does anyone know what I'm doing wrong or does anyone have a solution?Need help with Godfather 2
I think execution is not the same as killing. I just started playing the game, but I have already seen an option to ''execute'' a groggy enemy. Need help with Godfather 2
When it's saying execute, it means you have to almost waste him, then when a '' (Yellow) Execute)'' appears, press F, you will execute him...