George Zimmerman, the neighborhood watch vigilante who shot and killed Trayvon Martin on Feb. 22, 2012, is reported to be auctioning off the gun he used to kill the unarmed black teenager.

Zimmerman, 31, put the firearm up for sale on a gun broker website for an auction on Thursday, with a starting price at US$5,000.

The gun, a Kel-Tec PF-9 9mm, was recently returned to Zimmerman by the U.S. Department of Justice and he wrote on the auction site, "I am honored and humbled to announce the sale of an American Firearm Icon. The firearm for sale is the firearm that was used to defend my life and end the brutal attack from Trayvon Martin on 2/26/2012 … This is a piece of American History."

He also indicated that “many have expressed interest in owning and displaying the firearm including the Smithsonian Museum in Washington D.C.”

In an interview with an Orlando Fox affiliate, Zimmerman said he is “a free American. I can do what I like with my possessions.”

The Trayvon Martin foundation, set up after the youth’s death to “end senseless gun violence”, said it had “no comment on the actions of that person”.

Zimmerman said on the website that a portion of the proceeds raised would be used to "fight BLM [Black Lives Matter] violence against Law Enforcement officers, ensure the demise of [Zimmerman's prosecuting attorney] Angela Correy's persecution [sic] career and Hillary Clinton's anti-firearm rhetoric."

Zimmerman shot Martin after pursuing him for looking suspicious. Martin, who was visiting his father in the Sanford, Florida complex was returning from the store with a bag of Skittles and an iced tea.

As news of the killing spread, thousands of protesters across the country called for Zimmerman's arrest and a full investigation. Six weeks after the shooting, Zimmerman was finally arrested and charged with murder by a special prosecutor appointed by Governor Rick Scott.

Since Martin was killed while wearing a hoodie, hoodies were used to call attention to the racist nature of the killing at protests throughout the country. Professional athletes such as Carmelo Anthony, Dwyane Wade, LeBron James, and the entire Miami Heat team, took photos with hoodies in Martin's honor.

Zimmerman was acquitted of murder charges on July 13, 2013. On Feb. 24, 2015, the United States Department of Justice announced that "there was not enough evidence for a federal hate crime prosecution".