Joe Burbank / Pool via Orlando Sentinel/AP

George Zimmerman, left, sits with defense counsel at the Seminole County courthouse Tuesday in Sanford, Fla., on Dec. 11, 2012.

George Zimmerman is running out of money to pay for his legal defense, his lawyers say on a website set up to solicit donations.

Zimmerman, a former neighborhood watch volunteer, is charged with second-degree murder in the shooting death of Trayvon Martin, an unarmed black teenager, on Feb. 26, 2012, in Sanford, Fla. He has pleaded not guilty.

On Wednesday, Mark O’Mara’s firm, which runs the website GZDefenseFund.com, tweeted that there was an update to the site. In the update, the lawyers say they are preparing for a hearing on Zimmerman’s self-defense claim, possibly in April, but need money in order to pay legal expenses.

“The State has virtually unlimited resources to prosecute George,” the site reads. “To finance his defense, however, George relies on the generosity of individuals who believe he is innocent.”

“As we prepare for an (sic) Self-Defense Immunity Hearing or a trial, the cold fact is that we must raise more money,” the website reads. “Our goal is to raise $30,000 per month. This represents the minimum we calculate we need to conduct the defense George deserves, and this figure does not include any attorney's fees.”

The lawyers say on the website that as of a month ago more than $300,000 has been raised to pay for Zimmerman’s defense, but also say that when O’Mara first took the case last year, many legal analysts predicted the defense would cost more than $1 million.  The attorneys say neither O’Mara nor his co-counsel Mark West has been paid for their services.

This is how the, $314,099.07 raised by the defense fund has been spent, according to the site:

• Bail bond - $95,000
• Household/living expenses - $61,747.54
• Security - $56,100.00
• Law firm support and infrastructure - $40,647.64
• Case-related expenses - $35,588.07
• PayPal and fund management fees - $7,924.22
• Other expenses - $3,201.04

The site solicits donations via PayPal, credit card or check. The O’Mara Law Group in Orlando is the site’s registered owner. Zimmerman set up a website of his own to solicit money on April 8, 2012, but stopped taking donations when O’Mara launched gzdefensefund.com on April 23, 2012.

The Zimmerman case ignited an emotional debate over race and gun rights in the weeks after Martin's death. Local police initially did not charge Zimmerman, fueling protests, and Zimmerman was later charged by special state prosecutor Angela Corey following an investigation.

Zimmerman, who is of white and Hispanic descent, has pleaded not guilty to the murder charge. He says he shot Martin in self-defense after Martin attacked him. He is free on bail.

“It’s not unusual in high-profile cases for there to be a defense fund,” Derek Byrd, president of the Florida Association of Criminal Defense Lawyers told NBC News. “In the the old days people would go knocking on neighbors’ doors or ask friends. Today, with social media – Twitter, Facebook, websites – you can see where people would use them to reach a bigger audience.”

Byrd agreed with O’Mara that prosecutors can tap more resources for their case. He said defense attorneys have large expenses to hire experts, transcribe depositions and other related expenses.

E-mails sent to O'Mara's law firm were not returned, and repeated attempts to call his office phone met with a busy signal. E-mails and phone messages sent to prosecutor Corey were also unanswered.