For the executions that require you to press ( and gesture), note that your enemy must be low enough on health for it to work. Only performing the execution styles on mobsters will count toward the execution achievements.
Back of the Head Execution
Using a pistol, stand in front of your enemy, and while they are standing, lock onto them and press .
Barehanded Kneeling Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Then, without any weapons drawn, stand in front of your enemy, and while they are still kneeling, lock onto them and press .
Barehanded Standing Execution
Without any weapons drawn, stand in front of your enemy, and while they are standing, lock onto them and press .
Between the Eyes Execution
Using a revolver, stand in front of your enemy, and while they are standing, lock onto them and press .
Blackhand Execution
Kill your enemy with your fists without grabbing them.
Blackhand Grapple Execution
Kill your enemy with your fists while grabbing them.
Bombs Away Execution
Kill your enemy with dynamite, a bomb, an explosive barrel, or an explosive crate.
Bottle Execution
Kill your enemy by throwing a bottle at them.
Chin Up Execution
Using a 2x4, stand in front of your enemy, and while they are standing, lock onto them and press . 2x4s can be found by blowing up a burning barrel on the street.
Clavicle Crush Execution
Using a tire iron, stand in front of your enemy, and while they are standing, lock onto them and press .
Cocktail Hour Execution
Kill your enemy with a molotov.
Crooked Cop Execution
Using a police baton, stand in front of your enemy, and while they are standing, lock onto them and press .
Disarmed
Shoot your enemy in the shoulder to make them drop their weapon.
Double Play Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Then, using a baseball bat, stand in front of your enemy, and while they are still kneeling, lock onto them and press .
Faceoff Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Get right in front of them while holding a shotgun, lock on to them, and press .
Foot in Mouth Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Get right in front of them while holding a magnum, lock on to them, and press .
Gut Shot Execution
Using a shotgun, stand in front of your enemy, and while they are standing, lock onto them and press .
Hard Head Execution
Kill your enemy by slamming their head into a counter or other low object.
Hats Off Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Get right in front of them while holding a pistol, lock on to them, and press .
Headstrong Execution
Using a tommy gun, stand in front of your enemy, and while they are standing, lock onto them and press .
How's Your Leg Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Get right in front of them while holding a golf club or shovel, lock on to them, and press .
Kneecapped
Shoot your enemy in the knee.
Last Gasp Execution
Strangle your enemy to death with your bare hands.
Look at Me Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Then, using a revolver, stand in front of your enemy, and while they are still kneeling, lock onto them and press .
Magnum Execution
Kill your enemy with a magnum.
Melee Weapon Execution
Kill your enemy using any melee weapon.
Neck Boned Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Get right in front of them while holding a tire iron, lock on to them, and press .
Neck Kink Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Then, using a police baton, stand in front of your enemy, and while they are still kneeling, lock onto them and press .
Over Cooked Execution
Throw your enemy into a furnace by pushing them against the furnace and holding them over the edge then use the to throw them in the furnace. Furnaces can be found in bakeries and funeral homes.
Pipe Down Execution
Using a lead pipe, stand in front of your enemy, and while they are standing, lock onto them and press .
Pistol Execution
Kill your enemy with a pistol.
Protect Ya Neck Execution
Using a golf club or shovel, stand in front of your enemy, and while they are standing, lock onto them and press .
Revolver Execution
Kill your enemy with a revolver.
Riddled With Lead Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Get right in front of them while holding a tommy gun, lock on to them, and press .
Road Rage Execution
Kill your enemy by running them over with a car.
Shotgun Execution
Kill your enemy with a shotgun.
Sicilian Candle Execution
When your enemy is standing up. Get right in front of them while holding a 2x4, lock on to them, and press . 2x4s can be found by blowing up a burning barrel on the street.
Silent Assassin Execution
Strangle your enemy to death using the garrote wire.
Stained Glass Execution
Kill your enemy by throwing them through a window. Side Note: This execution is more easily obtained by lowering the health level of the gangster to about 1/4, pushing them against an unbroken window, holding them over the edge and using the to throw them through the window. Tried and true method.
Sure Shot Execution
Kill your enemy with a head shot.
Taste My Chamber Execution
Using a magnum, stand in front of your enemy, and while they are standing, lock onto them and press .
Tommy Gun Execution
Kill your enemy with a tommy gun.
Traffic Accident Execution
Kill your enemy by throwing them in front of a moving vehicle. Do not stand in front of traffic or it will stop - stand to the side of the road. By far the most difficult execution to pull off.
Wallpapered Execution
Kill your enemy by slamming them against a wall.
Watch Your Step Execution
Kill your enemy by throwing them off a roof, ledge, two-story window, etc.
Wrenched Execution
Get your enemy on their knees by shooting them in the knee or beating them down. Get right in front of them while holding a lead pipe, lock on to them, and press .
You're Out Execution
Using a baseball bat, stand in front of your enemy, and while they are standing, lock onto them and press . Note that on the screen it will call this a "Melee Standing Execution" even though there is no such thing.