This is believed to be the first time Zimmerman, 29, has been seen publicly since his acquittal on a second-degree murder charge in the 17-year-old Martin's death in February 2012. Zimmerman's parents and his attorneys have said in interviews since the verdict that they fear for his safety because of those who may not agree with it.
A message left at the office of Zimmerman attorney Mark O'Mara was not immediately returned Monday.
Robert Zimmerman, Jr. on Monday posted on his Twitter account about his brother's actions: "George saw a need, he acted. Our parents taught us to help, never to boast. Humility is George's finest trait."
Martin's shooting death spurred debate across the U.S. over racial profiling, self-defense and equal justice. Protesters nationwide lashed out against police in Sanford because it took 44 days for Zimmerman, a neighborhood watch volunteer, to be arrested last year. Many, including Martin's parents, said Zimmerman had racially profiled the unarmed black teen. Zimmerman, who identifies himself as Hispanic, said he acted in self-defense during a fight with Martin.
Six female jurors, whose names have not been released, considered nearly three weeks of often wildly conflicting testimony over who was the aggressor on the rainy night Martin was shot while walking through the gated townhouse community where he was staying and where Zimmerman lived.
The acquittal prompted rallies nationwide in the days afterward calling for a civil rights investigation and federal charges against Zimmerman.
It also led to a sit-in at Florida Gov. Rick Scott's office demanding that legislators repeal the state's stand-your-ground self-defense law. The law, passed in 2005, generally eliminated a person's duty to retreat in the face of a serious physical threat. At least 21 states have a self-defense law similar to Florida's.