SANFORD — After 3 1/2 hours of deliberations Friday, jurors in the George Zimmerman murder trial retired for the night, signaling that it may be a while before they reach a verdict.

The six-member panel — all women, five of them white — sent out a note at 5:50 p.m., asking to break for the evening.

When they get back to work at 9 a.m., they will resume the job of determining whether Zimmerman committed a crime when he shot and killed 17-year-old Trayvon Martin on Feb. 26, 2012, or whether the 29-year-old Neighborhood Watch volunteer was acting in self-defense.

Circuit Judge Debra S. Nelson told the jurors she would lock up their notes for the night and that they should not discuss the case until they return. That may be harder than it seems. They're sequestered, staying at the same hotel and are believed to be dining together.

When the jury returned to the courtroom just before retiring for the night, there were no outward signs of anger or conflict.

An hour and a half earlier they sent out a note asking for an itemized list of evidence exhibits — there are more than 250 in this case.

The judge had the clerk make some quick revisions to hers, and the judge sent back six copies.

Neither of the juror notes was good news for Zimmerman.

In his closing argument Friday, defense attorney Mark O'Mara asked jurors to start their deliberations with a quick check of whether they believed the defendant had acted in self-defense.

If they believed that, he said, there was nothing else for jurors to consider.

"It's an easy decision," he said.

Apparently not. If they followed his advice and were in agreement, they'd be done by now.

The panel must decide whether Zimmerman is guilty of second-degree murder, manslaughter or, because he acted in self-defense, committed no crime.

If they decide he's guilty of second-degree murder, Zimmerman faces a maximum sentence of life in prison. If they decide he's guilty of manslaughter, he faces up to 30 years.

Jurors may be hung up on manslaughter, a hard-to-explain offense that does not require a jury to find that the state proved Zimmerman acted out of ill will, hatred, spite or an evil intent, as second-degree murder would require.

For these jurors to convict Zimmerman of manslaughter, they would have to find that he committed an intentional act that killed Trayvon, and that the teen's death wasn't an act of justifiable or excusable homicide and didn't result from negligence.

When he presented his closing arguments, O'Mara told jurors he would "take on the obligation of proving to you that my client is innocent," despite the fact that the law doesn't require the defense to prove anything.

"If you have a reasonable doubt as to whether George Zimmerman was justified in the use of deadly force, he's not guilty," O'Mara told jury.

O'Mara on Friday described the shooting to jurors as "a tragedy, truly, but you can't allow sympathy into it."

Trayvon was the aggressor that night, he said.