George Zimmerman during the 21st day of his trial in Seminole circuit court, July 9, 2013 in Sanford, Fl.
Photo by Joe Burbank/Pool/Getty

George Zimmerman auctioning off gun used to kill Trayvon Martin

Updated

A listing to sell the gun used to kill Florida teenager Trayvon Martin no longer appeared online Thursday morning — just as the auction to buy it was set to begin.

The listing on GunBroker.com included a description written by George Zimmerman, a former neighborhood watch captain acquitted by a jury in the teen’s 2012 shooting death. The killing sparked a national conversation about race and “stand your ground” laws.

“This is a piece of American History,” Zimmerman says in the post.

Zimmerman’s brother, Robert, confirmed to NBC News that the gun sale is “legit.”

But at 11 a.m. ET, a link to the gun’s auction page showed a notification instead that the item is no longer in the system.

The firearm listed was a 9 mm Kel-Tec PF-9 pistol, and bidding was to start at $5,000.

In the post, Zimmerman, 32, said the Justice Department had recently returned the gun to him, and he has received offers from people who want to purchase it or put it on display: “However, the offers were to use the gun in a fashion I did not feel comfortable with.”

RELATED: George Zimmerman teams up with ‘Muslim-free zone’ gun shop owner to sell Confederate flag prints

A portion of the auction’s proceeds are supposed to “fight BLM (Black Lives Matter) violence against Law Enforcement officers” as well as “ensure the demise of … Hillary Clinton’s anti-firearm rhetoric.”

Clinton, the Democratic front-runner for president, said in a speech in April to the National Action Network that Zimmerman should never have had a gun.

Zimmerman killed Martin after he saw the unarmed 17-year-old walking through his gated Sanford community on Feb. 26, 2012, and did not recognize him. He confronted the boy, leading to an altercation and the shooting. Zimmerman claimed self-defense.

The death of Martin, who was African-American, set off a wave of protests.

Zimmerman at his 2013 trial was found not guilty of second-degree murder.

Neither Zimmerman nor his defense attorney immediately responded to requests for comment about the auction.

In an interview with FOX affiliate WOFL, Zimmerman said he is “a free American. I can do what I want with my possessions.”

“And if I sell it and it sells, I move past it,” he told the station. “Otherwise, it’s going in a safe for my grandkids never to be used or seen again.”

Benjamin Crump, an attorney for Martin’s parents, Sybrina Fulton and Tracy Martin, told NBC News on Thursday that it was “devastating” for them to learn the gun used to kill their son was to be auctioned off.

“It’s just shocking, it’s shocking to me and it’s shocking to everybody — and Trayvon to them is their child,” Crump said. “To everybody else, it may be a cause or a hashtag, but this is their son. So somebody’s actually talking about profiting from the loss of their child and it’s just very hurtful to them.”

He added that the family is remaining focused on the Trayvon Martin Foundation, with “its mission being to end the senseless gun violence in America.”

Zimmerman’s transition out of the public eye has not been without incident, and last year he was shot at by another driver during a confrontation on a Florida road. He was also arrested on assault charges against his girlfriend, although the charges were later dropped.

Zimmerman filed a defamation lawsuit against NBC News in 2012. A judge dismissed that claim in 2014. Zimmerman appealed, but a judge ruled against him.

—Micah Grimes contributed to this article.

This article first appeared on NBCNews.com

Black Lives Matter, George Zimmerman and Trayvon Martin

George Zimmerman auctioning off gun used to kill Trayvon Martin

Updated