The step-aunt and godmother of the late rapper Tupac Shakur, has become the first woman to be put on the FBI's most wanted terrorists list.
Joanne Chesimard, 65, now known as Assata Shakur, was convicted in 1977 of the murder of a New Jersey trooper on May 2, 1973.
Werner Foerster and a colleague stopped the former Black Liberation Army member and two others for a motor vehicle violation, and a gunfight broke out, authorities said.
Foerster, along with a passenger in the car with Chesimard, were killed in the gun battle.
During her trial and imprisonment, Chesimard, was represented by the late civil rights attorney William Kunstler, and some argue that she was a victim of racism and mistreatment.
Attorney Ron Kuby, who worked with Kunstler in the 1980s and interviewed Chesimard in Cuba in 1987, has disputed the FBI's notion that she poses a threat to the United States.
He said he did not think she had received a fair trial.
He told Reuters: "Let's not overstate the contours of this. Assata Shakur was the embodiment of the Black Panther Party and the Black Liberation Army at a time when there was a low intensity war between black radicals and the US".
The FBI have said that while there is no new threat from Chesimard, she is considered a "domestic terrorist".
The agency has also doubled the reward for her capture to $2 million.
Special agent Aaron Ford said: "Today, on the anniversary of Trooper Werner Foerster's death, we want the public to know that we will not rest until this fugitive is brought to justice".