Former neighbourhood watch volunteer George Zimmerman was released from jail Friday for a second time while he awaits his second-degree murder trial for fatally shooting Trayvon Martin.

Zimmerman left the Seminole County Jail a day after Circuit Judge Kenneth Lester granted a $1 million bail with strict conditions. He wore a white shirt and dress jacket as he walked out and got into an SUV, ignoring shouted questions from nearby reporters.

The judge is requiring Zimmerman to stay in Seminole County. He was allowed to leave Florida after his first release in April. Now he must be electronically monitored, can't open a bank account, obtain a passport or set foot on the grounds of the local airport. He has a 6 p.m. to 6 a.m. curfew.

"He's very happy to be out," Don West, one of Zimmerman's attorneys, told reporters outside the jail. "Certainly it's been a sobering experience spending the last month in jail in that kind of environment."

Zimmerman had been released on a $150,000 bond in April in the shooting of the unarmed black teenager, but the judge revoked it last month after prosecutors presented evidence that he and his wife misled the court about how much money they had available to pay for the bond. They didn't tell the judge that donations from a website for Zimmerman's legal defence had raised around $135,000 at the time of his first bond hearing.

Prosecutors argued Zimmerman and his wife talked in code during recorded jailhouse conversations about how to transfer the donations to different bank accounts. For example, George Zimmerman at one point asked how much money they had. She replied "$155." Prosecutors allege that was code for $155,000. Their reference to "Peter Pan" was code for the PayPal system through which the donations were made, prosecutors said.

Shellie Zimmerman faces arraignment at the end of the month on a perjury charge; she is free on bond.

Zimmerman's attorneys said Thursday that there was $211,000 in an account, which included the amount raised from Zimmerman's website and also money generated from another website set up by his legal team. An additional $20,000 was raised in the day after Lester issued the $1 million bond order.

Zimmerman had to pay a bond company $100,000 but also needed $1 million in collateral to secure the bail, his legal team said. West refused to comment on what was being used as collateral after Zimmerman left the jail.

"We worked that out," West said.

Zimmerman will stay in a "safe house" before relocating to a permanent home, and he has hired a security team, according to information posted on a website run by his legal team.

Shortly before Zimmerman's release, the Rev. Al Sharpton criticized Zimmerman for raising money through online donations. The civil rights leader and talk-show host was in New Orleans with Martin's parents, Tracy Martin and Sybrina Fulton.

"Now we see where they're soliciting money, saying, 'If you would have done the same thing, send money to help with his bond,' showing no remorse over the loss of human life," Sharpton said.

Court documents show that Zimmerman's parents are using their house as security for the bond. But Zimmerman likely didn't put up $1 million worth of collateral because the amount can be negotiated with the bond company and the insurance company backing the bond, said David Engel, an Orlando-area bail bondsman.

"Do they have a $1 million worth of collateral? I'm sure they don't," Engel said. "There's nothing set in stone regarding what we have to take. It's up to us what we decide between us and the insurance companies."

During Zimmerman's second bond hearing, his attorney, Mark O'Mara, said that his client was confused and fearful and experienced a moment of weakness when he and his wife misled the court. The judge didn't buy it and expressed his unhappiness with Zimmerman and his wife in his second bond order. He accused Zimmerman of making plans to flee to avoid prosecution, misleading O'Mara by not disclosing the money from the website and trying to manipulate the judicial system.

"Under any definition, the defendant has flaunted the system," Lester wrote.

But the judge said current law limited his ability to deny a second application for bond.

Zimmerman has pleaded not guilty to second-degree murder and claims the shooting was self-defence under the state's "stand your ground" law. Zimmerman and Martin got into an altercation last February inside a gated community in Sanford, Fla.

Zimmerman was the neighbourhood watch leader for the community and was tracking Martin, who was visiting his father's fiance, who lived there.

The "stand your ground" law allows individuals to use deadly force provided they are doing nothing illegal and it relieves them of a duty to retreat if they believe their lives are in jeopardy.

The law allows defendants to make their self-defence case at a hearing presided over by a judge and without the use of a jury.

If the judge deems self-defence was justified, the case can be dismissed without going to trial.

The 44 days between the shooting and Zimmerman's arrest inspired nationwide protests, led to the departure of the Sanford, Fla. police chief and prompted a U.S. Justice Department probe.

Martin's parents and supporters claim that the unarmed teenager was targeted because he was black and that Zimmerman started the confrontation that led to the shooting. Zimmerman's father is white and his mother is Hispanic.