TAMPA (FOX 13) - Murder defendant Orin Bivens is accused of shooting his ex-wife's husband, Alfred Lester to death.
He says he was calm when he did it.
Bivens says the victim was throwing around threats and being aggressive.
"He started saying he was goona kill me. I was afraid at that point on what could happen next," said Bivens.
Bivens says he tried to defuse the situation but it only escalated.
"I drew my weapon and I fired," said Bivens.
He missed but kept shooting.
"I saw him running up the stairs and I started firing up the stairs to try and stop him," said Bivens.
Bivens is now using Florida's Stand Your Ground law to try to dodge murder charges.
Under the law, you have a right to use deadly force if you feel your life is in imminent danger, without retreating.
But Prosecutor Stephen Udagawa says the victim had no weapon and was running away when he was shot in back.
"The defendant chased the victim and chased him, shooting at him," said Udagawa.
Prosecutors say the bad blood between the two men had been building for weeks and it came to a boil in June of 2015.
Neighbor Lovie Wilson was working from home and heard the two arguing.
"I also heard the gunshots," said Wilson.
Bivens is out on bail. If the judge agrees he was standing his ground, he walks away as a free man.
Judge is expected to rule soon.