Assata Shakur, convicted of killing a police officer, still wanted by FBI 40 years after fleeing to Cuba

Civil rights activist turned convicted murderer, Assata Shakur, continues to be a "top priority" for law enforcement officials, even 40 years after she was broken out of a Clifton, New Jersey, prison and fled to Cuba.

In May 1973, Shakur and two other members of the Black Liberation Army (BLA) were pulled over on the New Jersey Turnpike by State Trooper Werner Foerster and another highway officer. During a confrontation, a shootout ensued, killing Foerster and one of the passengers in the car.

In recognition of National Police Week, the FBI is highlighting seven cases involving violence against law enforcement officers, one of which involves Shakur. The agency referred to Shakur by her former name, Joanne Chesimard -- she changed her name in the 1960s after briefly joining the Black Panthers.

"This was a heinous execution of a law enforcement officer, cut and dry. This is without dispute," FBI's Special Agent in Charge Gregory Ehrie told ABC News.

Foerster was 34 at the time of his death, and left behind a wife and young son.

Shakur was convicted of first degree murder.

In 1979 -- two years into her life sentence -- she was broken free from prison with the help of other members of BLA and fled to Cuba, where Fidel Castro granted her asylum.

Since the U.S. does not have an extradition treaty with the country, Shakur seems untouchable as she enters her golden years.

"Ensuring Chesimard is safely brought back to New Jersey to finish her sentence is our top priority," said Ehrie.

In 2015, after President Barack Obama opened U.S. communications with Cuba, the country has helped Ehrie and his team with another case. In November 2018, John Ray III fled to Cuba after allegedly killing his girlfriend. Even without an extradition treaty, the FBI was able to communicate with law enforcement officials in Cuba and negotiate Ray's return to the U.S. to face the charges.

With that in mind, Ehrie wants Shakur to know that her days of living free could be numbered.

Shakur made history by becoming the first woman to make the FBI's most-wanted list and is still revered by some groups, including the Women's March, for her anti-sexism and anti-racism activism prior to the murder.

But for people like New Jersey State Trooper Colonel Patrick J. Callahan, her most defining act remains the murder of Foerster.

"There's always an alternate narrative," said Callahan, who grew up in a law enforcement family and heard about Foerster’s murder as a child. "She is a domestic terrorist and a convicted killer, that is the truth. There's certainly a difference between that and a civil rights activist. There's certainly civil rights activist in our history who have moved the narrative forward, she did not."

Decades later, Foerster's family still mourns his death.

"It is still raw and painful for them today," Callahan told ABC News. "So that's why we are here to make sure that we do everything we can to have her serve out her sentence."

There's a $2 million reward for any information that leads to the now-71-year-old's capture.