Zimmerman is charged with second-degree murder, but the jury will also be allowed to consider manslaughter. Under Florida's laws involving gun crimes, a conviction on either could mean life in prison.
The jurors have been sequestered during the past three weeks. Because there were no eyewitnesses to the shooting, jurors will likely rely heavily on testimony from police, neighbors, friends and family members. The testimony was often conflicting.
Jurors will have to determine whether Zimmerman took the law into his own hands or was in a fight for his life and shot Martin in self-defense.
Earlier report 12:07 p.m.:
SANFORD, Fla. — The prosecution has begun it's rebuttal to the defense's closing arguments in George Zimmerman's second-degree murder trial.
Prosecutor John Guy on Friday began countering defense attorney Mark O'Mara's contention that Zimmerman shot Trayvon Martin in self-defense.
O'Mara said the prosecution's case was full of gaps and built upon a series of "could've beens" and "maybes." He told jurors the burden was on prosecutors, and he said they hadn't proven Zimmerman's guilt beyond a reasonable doubt.
A jury of six women could begin deliberations as early as Friday afternoon.
Zimmerman is charged with second-degree murder, but jurors can also choose manslaughter. A conviction on either charge carries a maximum penalty of life in prison.