TRENTON, N.J. — A black New Jersey state trooper claims he was wrongly fired because he promoted a T-shirt on social media that bore the image of a fugitive convicted in the murder of a trooper in 1973.

Nyron Harris called the Instagram post an “honest mistake,” claiming he didn’t realize Joanne Chesimard’s image was on the shirt. Harris said he was helping promote his cousin’s clothing company, which sold the “Black Excellence” shirts, but claims the image outraged current and retired troopers and staffers and that anger led to his firing.

NJ.com reports Harris filed a discrimination lawsuit in December, claiming white troopers accused of far worse behavior were allowed to stay on the force. He also contends that superiors drummed up minor infractions to justify turning him away from the statewide force when he was up for reenlistment last summer.

Harris joined the state police in 2013. Under state regulations, newly hired troopers go through a five-year probationary period and can be denied reenlistment for cause. However, the official reason for Harris’ firing is unclear, according to the report.

State Police and the Attorney General’s Office declined comment on the suit.

Chesimard was convicted in the death of Trooper Werner Foerster. He was killed during a gunfight after a traffic stop on the New Jersey Turnpike.

Chesimard was sentenced to life in prison but escaped in November 1979 and eventually traveled to Cuba. Fidel Castro granted her asylum and she has been living there under the name Assata Shakur and is the first woman placed on the FBI’s Most Wanted Terrorist List.

In the years since her escape, New Jersey governors and state leaders have urged federal officials to call for her return to the United States.