This is the first mission in Colonel Cortez's mission line.
Cortez sits down to a plate of lobster, and offers Tommy some. Nevertheless, the two talk about the deal. It turns out that one of Cortez's right-hands, Gonzalez, may have mentioned the deal before it went down. Cortez has tired of him, labelling him an incompetent fool, and hands Tommy a chainsaw to take him out at his penthouse.
Head to the penthouse north of The Malibu Club, where Gonzalez is residing. You automatically equip the Chainsaw upon entering. He will flee, so let him exit the penthouse, and exit yourself when prompted. He will run down the street, and this is a good time to knock him to the ground with your fists, before taking out the Chainsaw and finishing him off.
When Gonzalez is slain, you get a 2-Star Wanted Level. Head to the Pay 'n' Spray to the north for a free paint job to finish up.
Mission Passed: $250