Assistant State Attorney Leah Klein said in an opening statement Tuesday that Medina shot Alfonso eight times during an argument in their home. Klein said Alfonso had threatened to leave him and that, as an undefeated, 200-pound amateur boxer who was much larger than his 5-foot-6 wife, he would never let her go.
"He never lost a fight. He wasn't going to lose to his wife. He wasn't going to lose by letting her leave as she said she was going to do," Klein said.
The Facebook posting, she added, was his way of claiming that victory. Medina, 33, also admitted the shooting in that posting, adding that his wife had assaulted him prior to the killing.
"He did what people do when they win," Klein said of the posting. "He did what was good for him."
Defense attorney Saam Zanganeh deferred an opening statement. The defense focuses on claims Alfonso abused drugs, battered her husband and was involved in Satan worship, causing Medina to fear her, which led to the shooting.
One early witness, Paul Ampudia, was a manager at the property firm where Medina worked the day of the killing. Ampudia testified that Medina called that morning to say he had killed his wife and was going to turn himself in to police -- but also mentioned that she had been punching him.
"He said there was years of abuse and he wasn't going to take it anymore. He said she was punching him," Ampudia said.
Medina and Alfonso had a tumultuous relationship, marrying and divorcing and then marrying again, court records show. The argument that led to the shooting began in their bedroom, where authorities say Medina first threatened his wife with a gun when she threw mascara and towels at him.
It ended in the kitchen, where Medina claims he was threatened with a knife, leading him to go back upstairs for his gun followed by the fatal shooting. A video surveillance camera captured some of the argument. Police say Alfonso's body was found in a position indicating she was cowering in fear.
The trial is expected to take about two weeks. Medina, who turned himself in to police shortly after the shooting, faces life in prison if convicted, and he is also charged with child neglect because Alfonso's 10-year-old daughter was in the home at the time of the slaying.
Officer Frank Moreno of the Miami-Dade Police Department said investigators were forced to break down the front door of the couple's home with a sledgehammer and an axe. Moreno said he found the girl upstairs in a bedroom watching television with the volume up loud.
Moreno said he wrapped the child in a red blanket and carried her out of the house, shielding her from seeing her mother's body in the kitchen.
"I wrapped her with a blanket completely. I brought her down the rest of the stairway," Moreno told the jury. "My body would prevent her from seeing what was behind me."