He was convicted of trying to overthrow the government, and named a leader of a terrorist group that bombed public buildings and killed people.

Now, President Obama's decision to commute the sentence of FALN member Oscar Lopez Rivera has sparked outrage from terror victims.

"I'm disgusted by what the president did. It's a travesty," said Joe Connor, whose father was killed in an infamous FALN terrorist bombing in Manhattan.

"The enemies of our country are being rewarded, and being treated as if they are heroes. What we hear is that Oscar Lopez Rivera did not get to know his family. Well, neither did my father. The victims and the Americans get pushed aside."

Rivera has been serving a 55-year federal prison sentence for being a leader of the Puerto Rican terrorist group, which sought independence for the U.S. island territory. The FALN claimed responsibility for over 70 bombings in New York City, Washington, D.C., and Chicago from 1974 to 1983. The attacks killed five people and wounded dozens more, including police officers.

In 1981, Lopez Rivera was convicted of seditious conspiracy to overthrow the U.S. government and arms trafficking. He was later sentenced to serve 15 more years behind bars for trying to escape twice, and he never renounced his radical cause.

In 1999, on the eve of Hillary Clinton's U.S. Senate run in New York, her husband, President Clinton, commuted the sentences of 16 imprisoned FALN members. But Lopez Rivera reportedly turned the offer down, refusing to be released unless all of his comrades were released from prison.

Now, 18 years later, he will be walking out of the federal prison in Terre Haute, Ind., a free man, his sentence cut short by 34 years.

"I went to his parole hearing in 2011," said Connor. "We were looking for some sort of reconciliation, some sort of admission, some sort of atonement. We didn't get any of that. He is a sworn terrorist, and for the president to release a sworn terrorist for political reasons, or whatever reason, is a disgrace."

Joe was only 9 years old when his father Frank went to have lunch at the historic Fraunces Tavern, near Wall Street, on Jan. 24, 1975. The colonial landmark is where President George Washington bid farewell to his troops on Dec. 4, 1783. That is why the symbol of the nation was targeted.

As Frank had lunch, a bomb suddenly exploded, killing him and three others. More than 60 people were injured. Frank Connor was 33 years old, and since then his son has taken up the crusade to speak out against terrorism and freedom for the killers. He says Lopez Rivera never admitted or accepted responsibility for his acts, never expressed any remorse, and that the president's decision sends a horrible message.

"It does nothing but encourage terrorism, it makes you think that at some point, terrorism will be forgiven," he said.

Lopez Rivera has become a cause célèbre among some Latino officials and celebrities, who have claimed he is a freedom fighter unfairly imprisoned for his political beliefs. His supporters range from Broadway's "Hamilton" creator Lin Manuel Miranda to several members of Congress, the mayor of San Juan, the speaker of the New York City Council, and Archbishop Desmond Tutu of South Africa. More than 100,000 people signed a petition urging Obama to grant the clemency.

“I think it is an historic moment for the Puerto Rican people," said Lopez Rivera's brother, Jose, who lives in Chicago.

"It's a moment where we can say the president of the United States, this President Obama, has really shown that we have to reach a level of reconciliation. My brother went to prison and charged with seditious conspiracy for exposing the fact that the U.S. is a colonial power in Puerto Rico," he said.

Connor countered, "There are no political prisoners, the United States does not hold political prisoners, these were terrorists."

Connor is also calling for the extradition of American fugitives from Cuba, including convicted cop killer and Black Liberation Army member Joanne Chesimard and FALN chief bomb maker Willie Morales. Morales has been called the suspected mastermind of the Fraunces Tavern bombing that killed Joe's father and he remains protected by the Castro regime even as he is on the FBI's Most Wanted List with a $100,000 reward offered for his capture.

"We have 70 or 80 fugitives in Cuba, and we have to now look to the Trump administration and say, hey we have to bring back Willie Morales," Connor said.

"We need justice, and my father deserved that justice. He was a good man, and the rest of the people who were murdered by the FALN deserve justice."

Lopez Rivera will walk out of prison a free man on May 17, and President Trump, by U.S. law, will not be able to reverse the decision.

Follow Eric Shawn on Twitter @EricShawnTV

Fox News’ Jen Oliva contributed to this report.