Criminal Legal Process

Please read the following case scenario below. You will be using these facts over the next 7 weeks. The case heading and type of case is listed below.
PEOPLE OF THE STATE OF TEXAS, Plaintiff
VS.
Scott Mayo, Defendant
TYPE OF CASE-Criminal
SUMMARY OF FACTS
Scott Mayo worked as a bartender at The Local Watering Hole. One night at work, Scott got into an argument with Basil Scowen. Mayo owed Scowen $1500.00. The argument heated up and, after Scowen picked up a beer bottle threateningly and appeared to be intoxicated, Mayo grabbed a pistol kept behind the bar and fired at Scowen, killing him. Mayo says Scowen told him, “I am going to kill you,” and what he believed was imminent danger from Scowen.  Mayo was placed under arrest. He was not read his rights. He was transported to the local county jail. The prosecution witnesses are the police officer, who came to the scene and took statements from Mayo, and a frequent bar customer, Dawn Dietz, who witnessed some of what happened. The defense witnesses are the defendant, Mayo, and Joe, “the fireman”, who was outside and saw some of the action through the window while sitting on the patio.
Based on the facts provided to you, if you are the prosecutor, what will you charge Mayo with using Florida state law guidelines? Please discuss why in your response, providing a detailed analysis of how you reached your decision on the charge(s).