The agent, Navin Kalicharan, was off duty and fired at the man from a second-story window, hitting him in the back in July 2012.
The man claimed that he was running away when the agent shot him, but a government investigation concluded otherwise.
Still, the bureau deemed the decision to fire a "bad shoot", in agents' parlance, a report in the New York Times said.
The bureau faulted the agent for violating its lethal force policy about six months after The Times reported that the FBI had found to be justified at least 150 consecutive shooting episodes dating at least to 1993.
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The disclosure of the disciplinary action against Kalicharan, who is fighting the dismissal, comes at a time of heightened national scrutiny of shootings by law enforcement officials.
Under the FBI's lethal force policy, agents may fire their weapons only if there is an imminent risk of death or serious bodily injury.
The panel unanimously concluded that Kalicharan had violated the lethal force policy and said it appeared that the agent had been worried not about his own safety, but instead "was concerned about his car".
Kalicharan's lawyer Lawrence Berger said his client would be vindicated after a hearing to appeal the decision to dismiss him.
"We are vigorously defending his tenure, and we are vigorously defending the shoot," Berger said in the Times report.
Kalicharan said he feared that Ricketts was going to shoot. Investigators however found no evidence that Ricketts, then 23, was armed.