After enduring more than three decades in a Chicago prison, Oscar López Rivera has been pardoned by Barack Obama.

The Puerto Rican independence activist, who is deemed to be one of the world’s longest-serving political prisoners, was serving a 70-year sentence and has been imprisoned since 1981.

In his final days in office, Mr Obama has issued 64 pardons and 209 commutations, including granting the release of Chelsea Manning. The transgender US Army private, who was jailed in 2010 after handing thousands of secret documents to WikiLeaks, will now be freed on 17 May instead of her scheduled 2045 release.

He was a well-respected grassroots Puerto Rican activist

Born in San Sebastian in Puerto Rico in 1943, López Rivera's family moved to the mainland US when he was just nine years old. At the age of 14, he moved to Chicago with his sister. By the time he turned 18, he was drafted into the army, going on to serve in the Vietnam War and being awarded the Bronze Star.

After returning from the war, López Rivera became a leading grassroots activist in the area. He fought against discrimination, exploitation and police brutality in Puerto Rican communities in the late 1960s. On top of this, he was instrumental in the creation of both the Puerto Rican High School and the Puerto Rican Cultural Center and played a key role in campaigning for bilingual education in schools and urging universities to actively recruit members of the Latino population.

Protesters urge Obama to commute Chelsea Manning's sentence Show all 12 1 /12 Protesters urge Obama to commute Chelsea Manning's sentence Protesters urge Obama to commute Chelsea Manning's sentence torbakhopper/Flickr Protesters urge Obama to commute Chelsea Manning's sentence Garry Knight/Flickr Protesters urge Obama to commute Chelsea Manning's sentence People hold signs calling for the release of imprisoned wikileaks whistleblower Chelsea Manning while marching in a gay pride parade in San Francisco, California June 28, 2015. Manning has appealed to an Army court to overturn her court-martial conviction, a court filing released on Thursday said. Reuters Protesters urge Obama to commute Chelsea Manning's sentence Around twenty activists associated with the Chelsea Manning support group rally in front of the White House in Washington DC, Sunday May 11, 2014. Stephen Melkisethian/Flickr Protesters urge Obama to commute Chelsea Manning's sentence Daily Chalkupy/Flickr Protesters urge Obama to commute Chelsea Manning's sentence Around twenty activists associated with the Chelsea Manning support group rally in front of the White House in Washington DC, Sunday May 11, 2014. Protesters urge Obama to commute Chelsea Manning's sentence Twitter Protesters urge Obama to commute Chelsea Manning's sentence Abigail Edward holds up a sign advocating the release of WikiLeaks whistle blower Chelsea Manning along the Gay Pride parade route in San Francisco, California on Sunday, June, 26, 2016. Josh Edelson/AFP/Getty Images Protesters urge Obama to commute Chelsea Manning's sentence Demonstration for Chelsea Manning in London, England, United Kingdom. Chelsea Manning (born Bradley Edward Manning) is a United States Army soldier who was convicted by court-martial in July 2013 of violations of the Espionage Act and other offenses, after disclosing to WikiLeaks nearly three-quarters of a million classified or unclassified but sensitive military and diplomatic documents. Manning was sentenced in August 2013 to 35 years imprisonment, with the possibility of parole in the eighth year, and to be dishonorably discharged from the Army. Manning is a trans woman who, in a statement the day after sentencing, said she had felt female since childhood, wanted to be known as Chelsea, and desired to begin hormone replacement therapy. From early life and through much of her Army life, Manning was known as Bradley; she was diagnosed with gender identity disorder while in the Army. Mike Kemp/Getty Protesters urge Obama to commute Chelsea Manning's sentence Chelsea M Queer Friends/Twitter Protesters urge Obama to commute Chelsea Manning's sentence Instagram Protesters urge Obama to commute Chelsea Manning's sentence Jil Love Revolution/Instagram

Convicted of "seditious conspiracy"

López Rivera was convicted of “seditious conspiracy” for plotting to overthrow the US government in 1981 and sentenced to 55 years in prison. In 1988 he was sentenced to an additional 15 years in prison for conspiring to escape from the Leavenworth federal prison. Law enforcement labels have labelled him a terrorist since the 1970s.

He was a member of Armed Forces of National Liberation, better known by its Spanish acronym FALN, and was one of more than a dozen group members convicted in the 1980s.

US prosecutors accused the group of being responsible for 140 bombings on military bases, government offices and financial buildings, but López Rivera has repeatedly and strenuously denied being involved.

He has repeatedly insisted he poured his energies into activism which did not imperil people’s lives.

Bill Clinton offered him clemency but he declined

President Bill Clinton offered him and other members of the FALN clemency in 1999, prompting an emotionally charged national debate in the US. At the time, Mr Clinton said their sentences were not proportionate to their offences.

But Lopez Rivera turned down the chance to reduce his sentence because it did not include all of the group’s members, his lawyer, Jan Susler, revealed at the time. However, 12 prisoners accepted the offer and were released. If he had accepted the agreement, she said he would have been eligible to be freed in 2009.

If Mr Obama had not decided to pardon López Rivera he would have been imprisoned until 26 June 2023, which is five months after his 80th birthday.

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His release sparked celebration from supporters

His release has prompted an outpouring of celebration from his supporters.

Lin-Manuel Miranda, the creator of the Broadway musical Hamilton applauded the news on Twitter: “Sobbing with gratitude here in London. OSCAR LOPEZ RIVERA IS COMING HOME. THANK YOU, @POTUS.”

“Today my little island is the happiest. Thank you President Obama for liberating our Oscar Lopez,” wrote Ricky Martin.