SANFORD, Fla. -

When it comes to crime and guns in Florida, a lesser charge does not always mean a lesser sentence. This is why attorneys in the George Zimmerman trial had a heated argument Thursday morning.

The prosecution threw a curve ball that surprised the defense and displayed a lack of confidence in the second-degree murder charge. They pushed for the judge to instruct the jury to consider two lesser charges.  Defense attorneys objected.

Prosecutors considered aggravated assault Wednesday, but by Thursday morning they had changed their mind to third-degree murder. Before the judge said the charge would not be read to the jurors, defense attorney Don West's outrage was felt in the courtroom.

In a flash of anger, West put his cup down and said: "Oh my God! Just when I thought this case couldn't get more bizarre!"

Prosecutor Richard Mantei continued to explain the standards that would have to be met for the jurors to consider the third-degree murder charge. The mention of a child abuse standard pushed West to the edge.

"Judge this was a trick!" West said. "Doesn't the court realize this was a trick from the State?"

Judge Debra Nelson asked West to avoid using the word "trick" and to "stop jumping up and down." Defense attorney Mark O'Mara was not in court Thursday morning to calm West down. He was preparing for the closing statement.

On Wednesday, O'Mara held a press conference.

"Self-defense is self-defense," defense attorney Mark O'Mara said. "What happened out there was not a crime, so in that context there shouldn't have been" any charges.

When the trial began June 10, prosecutors sought a second-degree murder charge. Thursday they were seeking the lesser charges of manslaughter and the lesser felony third-degree murder charge. West believed the change was planned; Nelson disagreed.

"The facts did not support an aggravated assault lesser included offense," Nelson said.

Zimmerman claims he killed 17-year-old Trayvon Martin Feb. 26, 2012 in self-defense. He used a Kel-Tec 9 mm handgun to shoot the unarmed teen in the chest, he told police, because Trayvon punched him, was smashing his head against the cement and moving for his gun.  If his self-defense claim stands, he can go free.

But if he is found guilty, it's likely that he will go to prison. Florida’s 10-20-Life law imposes mandatory minimum sentences that are harsher for crimes involving the use of a handgun, prosecutor Angela Corey said.

Jurors determine when the law is applicable.

“Use a gun and you are done,” was the campaign slogan for the law when Gov. Jeb Bush signed. It went into effect in 1999.

If the jury finds him guilty of second-degree murder, Zimmerman could go to prison for life. The sentences for the two lesser charges are as severe.

Manslaughter in a case involving a gun is considered a first-degree felony. The sentencing could range from 25 to 30 years in prison or 30 years of probation. Nelson included it in the jury instructions.

Third-degree murder charge in a case involving a gun is also considered a first-degree felony.  The sentencing could range from 25 years to life in prison.  Nelson did not include the charge in the jury instructions.

Corey has experience with the 10-20 Life law. In 2009, U.S. Army veteran Ronald Thompson, 65, of Keystone Heights, Fla., fired shots to scare off teens.

Corey prosecuted Thompson on an aggravated assault charge. With the help of the 10-20 Life law, she fought to increase a three year sentence to 20 years. Fourth Circuit Judge John Skinner refused to apply the 10-20-Life law and sentenced Thompson to three years.

Corey won an appeal and he was sentenced to 20 years. But in 2012, Fourth Circuit Judge Don Lester ruled that the jury instructions were not clear. Thompson was freed and is waiting for a new trial.

Corey will be paying special attention to the jury instructions in Zimmerman’s trial.

Prosecutors will be presenting their closing arguments Thursday. The defense will follow, and then prosecutors will present a rebuttal.

The case will be in the jurors' hands by Friday afternoon, and they are expected to deliberate over the weekend.