Five key issues for Zimmerman jury

• In the end%2C will jurors - and the nation - have the answers they%27ve been waiting for%3F
• Five key points will guide the fate of George Zimmerman as jurors deliberate
• The killing of Trayvon Martin has polarized many

George Zimmerman could spend the rest of his life in prison or walk away a free man after more than a year of being reviled as a murderer.

During three weeks of testimony, state prosecutors called 38 people to the stand to paint Zimmerman as a spiteful, frustrated man who profiled and killed an unarmed teenager. Defense attorneys countered by calling 18 witnesses -- but not Zimmerman -- to explain that Zimmerman feared for his life and was being pummeled by Trayvon Martin.

When the fatal gunshot was fired in the dark, nobody was close enough to see what happened -- other than Zimmerman and Trayvon. Throughout the trial, prosecutors tried to shine some light on that night and show jurors what they believe happened, but most experts think there were few concrete answers in the testimony.

"They are making it a guessing game, and guessing games favor the defense," Jose Baez, a Florida criminal defense attorney, said of both sides. Baez successfully defended Casey Anthony, a Florida mother accused of killing her daughter in a high-profile murder case.

Zimmerman, 29, has pleaded not guilty to a second-degree murder. He also faces a charge of manslaughter after some last-minute maneuvering by prosecutors. Second-degree murder in Florida carries a possible life sentence. If convicted of manslaughter, Zimmerman could get up to 30 years.

Speculation that Zimmerman, who is Hispanic, profiled, followed and murdered the black teen sparked racial controversy and protests across the nation last year. Zimmerman says that race did not factor into his actions and that he acted in self-defense after Trayvon sucker-punched him and began beating him.

Most legal experts interviewed by USA TODAY agree with Baez and say the prosecution largely failed at its attempt to prove Zimmerman committed second-degree murder. Several, however, added that jurors may still weigh heavily that Zimmerman followed and later shot a teen walking home carrying Skittles and iced tea.

Which scenario becomes reality depends largely on five key issues before the jury deciding his fate.

-- Whether Zimmerman acted in self-defense.

Defense attorneys have maintained that Zimmerman was in fear for his life when he shot Trayvon Martin. Throughout the trial they painted Zimmerman as a hardworking, quiet, calm man who started a neighborhood watch group to help his community.

"There's enormous evidence that my client acted in self-defense," Mark O'Mara, Zimmerman's attorney, said last week. "There is no other reasonable hypothesis."

The night of the shooting, O'Mara said Zimmerman was being the eyes and ears of his community and called police when he saw someone suspicious. Soon after, he found himself fighting for his life because Trayvon overreacted and used the environment around him to beat Zimmerman, the lawyer said.

"That is not an unarmed teenager," O'Mara said in his closing statement, explaining with an actual concrete slab that Trayvon used his fists and a sidewalk to threaten great bodily harm.

According to Florida law, O'Mara said Zimmerman did not need to be greatly injured -- just threatened.

Prosecutors worked hard to convince the jury that Zimmerman wasn't fighting for his life and was in fact shooting an unarmed teenager. In his rebuttal Friday, Assistant State Attorney John Guy put up a split screen of pictures: Trayvon's dead body on the grass and the bloody head of George Zimmerman after the shooting.

"Who lost the fight?" Guy asked. He added that if Zimmerman is acquitted it will send a message that grown men can follow and kill children.

-- Zimmerman's pursuit of Trayvon.

While Zimmerman was on the phone with a police dispatcher, he began following Trayvon. Soon after, the dispatcher told Zimmerman it was not necessary for him to pursue the teen.

The prosecution's most important witness may have been Rachel Jeantel, 19, a young woman who was on the phone with Trayvon moments before he died.

Jeantel said Zimmerman stared at and then followed Trayvon, who tried several times to run away. Trayvon was out of breath, she said. "It was kind of strange that a person kept watching and following," she said. "It was like being stalked."

Jurors, the judge and defense attorney Don West, however, had a hard time understanding Jeantel as she spoke. That may hurt her credibility, said Susan Constantine, a jury consultant and body language expert who was in court during Jeantel's testimony.

"Jurors struggled and struggled and then they got to the point where they disengaged," Constantine said.

In his closing statement Thursday, prosecutor Bernie de la Rionda urged jurors to treat her fairly and disregard her colorful language and presentation. "She should be judged not by the color of her personality but by the content of her testimony," de la Rionda said.

Throughout the trial, O'Mara maintained Zimmerman stopped following Trayvon once police told him it was not necessary. The state, O'Mara told jurors, can't prove that Zimmerman did otherwise.

"Don't make assumptions," O'Mara said. "If you don't know it, it hasn't been proven."

-- Who initiated the confrontation?

While it's clear there was some sort of confrontation, jurors will have to decide who caused that fight.

In his closing statement, O'Mara showed jurors a computer animation of Trayvon walking up to Zimmerman and punching him. O'Mara added that Trayvon had time to go home, but instead likely hid, waited for Zimmerman and confronted him. He said the teen may have been charged with aggravated battery had he survived the shooting.

"Trayvon Martin came towards George Zimmerman," O'Mara said.

State attorneys are hoping the jury will believe Jeantel's version of what happened.

Jeantel recalled Trayvon saying, "Why are you following me?"

She continued, "Then I heard a hard-breathing man say, 'What are you doing around here?' "

Jeantel then heard a bump and heard Trayvon saying, "Get off. Get off," she said. Seconds later, the phone disconnected, and when she called back, she got no answer.

Three days later, Jeantel said, she learned Trayvon was dead.

Prosecutors called several law enforcement officials and forensic experts who said Zimmerman was the aggressor.

-- The person on top when the shooting occurred.

Both sides admit there was a fight. Zimmerman says Trayvon was pummeling him when Zimmerman shot the teen.

Eyewitness Jonathan Good said he saw Trayvon on top of and striking Zimmerman moments before the teen was shot. It was a statement he told police the night of the shooting and one he stuck with when addressing the jury.

However, Selma Mora, who lived a couple of houses down from Good, said a person straddling another person told her to call police. Minutes later, the same person who was on top, whom she identified as Zimmerman, was on his feet after a gunshot, Mora said.

-- The voice heard screaming on a 911 tape.

A 911 call recorded screams and the fatal gunshot moments before the shooting. Who was screaming is a critical question before the jury.

The defense called nine people -- including both of Zimmerman's parents -- to testify that the screams belonged to Zimmerman.

Zimmerman's father, Robert Zimmerman, Sr., was the last to testify that the voice heard screaming on a 911 call was George Zimmerman. "It's my son," he said.

The prosecution called both of Trayvon's parents, who said their son was screaming moments before he was shot.

Tracy Martin, Trayvon's dad, testified he listened to the 911 call at least 20 times at the Sanford mayor's office. After that, he said, he was convinced the voice screaming was Trayvon's.

"I was listening to my son's last cry for help," Tracy Martin said. "I was listening to his life being taken."