George Zimmerman is selling the gun he used to kill Trayvon Martin, an unarmed black teenager, during a 2012 confrontation in Sanford, Florida.
"I'm a free American," he told Fox 35 in Orlando. "I can do what I like with my possessions."
Zimmerman wrote in the auction description of the Kel-Tec PF-9 9mm handgun that he plans to use some of the money to "fight BLM violence against Law Enforcement officers, ensure the demise of Angela Correy's [sic] persecution career and Hillary Clinton's anti-firearm rhetoric."
Angela Corey is the Republican state attorney who charged Zimmerman with second-degree murder in the Martin shooting.
The auction begins Thursday morning on GunBroker.com with a starting bid of $5,000.
In the description, Zimmerman said the gun was used to "defend my life."
It has recently been returned to me by the Department of Justice. The pistol currently has the case number written on it in silver permanent marker. Many have expressed interest in owning and displaying the firearm including The Smithsonian Museum in Washington D.C. This is a piece of American History.
However, the Smithsonian Museum tweeted on Thursday it had "never expressed interest" in the weapon.
Zimmerman said he had received offers for the gun, but "the offers were to use the gun in a fashion I did not feel comfortable with."
He did not elaborate.
"The firearm is fully functional as the attempts by the Department of Justice on behalf of B. Hussein Obama to render the firearm inoperable were thwarted by my phenomenal Defense Attorney," he added.
He ended the auction description with "Si Vis Pacem Para Bellum," Latin for "if you wish peace, prepare for war."
Zimmerman has been in and out of trouble repeatedly since his acquittal, including a number of arrests documented by Fusion.
He has also attempted to provoke his critics by selling prints of his painting of a Confederate flag, calling President Barack Obama an "ignorant baboon" and tweeting a photo of Martin's body.
The Trayvon Martin Foundation did not want to address "that person," telling Fox 35 that the organization is focused on "ending senseless gun violence."
"This election season, we are laser focused on furthering that mission," the group said. "As such, the foundation has no comment on the actions of that person."
In a statement released Thursday, Rep. Hakeem Jeffries (D-N.Y.) reacted to the news, saying: "Trayvon Martin's cold-blooded killer should be in prison."
"It should shock the conscience of every decent American that this man is peddling his murder weapon for sale," he added. "America must reject this merchant of death once and for all.”
This article has been updated with additional information on Hakeem Jeffries' statement and the Smithsonian's response about auctioning the firearm.