Oscar López Rivera, the mastermind of Puerto Rican nationalist group FALN, placed more than 130 bombs throughout the United States, most concentrated in New York and Chicago.

Outgoing President Barack Obama, nonetheless, commuted López Rivera’s sentence, allowing him to be freed in May, despite his sentence still requiring him to serve 30 additional years.

A 1999 House report for the Committee on Government Reform revealed that the bombings, deemed terrorist attacks, killed at least five people and wounded dozens more, in addition to causing more than $3 million in property damage.

Nevertheless, CNN notes that “multiple groups, including the Congressional Hispanic Caucus, the Congressional Black Caucus and other elected officials lobbied the Obama administration for López Rivera’s release.”

On Tuesday, Obama announced that Rivera will be liberated on May 17 as one of 209 grants of commutation by the outgoing President. The terrorist’s prison sentence was expected to expire in 2051.

“I am an enemy of the United States government,” 74-year-old Rivera, who has served 35 years of a 70-year sentence for seditious conspiracy, weapons-related charges, and a prison escape plot, told a federal judge in 1983, reports the New York Daily News, which notes that “there is no evidence that he’s changed his mind.”

Seditious conspiracy refers to a charge used for those plotting to overthrow the U.S. government.

During the 1970s and 1980s, FALN, the Spanish acronym for the Armed Forces of National Liberation, planted bombs in U.S. cities, in addition to plotting additional bombings, prison escapes, and armed robberies.

“Their goal was to destabilize what they called the ‘Yankee capitalist monopoly’ and achieve Puerto Rican independence,” notes the Daily News. “Their method was terrorism.”

When then-President Bill Clinton offered to commute his sentence in 1999, Rivera reportedly refused to abide by the condition that he renounce his terrorist past.

“The whole thing of contrition, atonement, I have problems with that,” he told a reporter in 1998.

Rivera’s supporters consider him a “political prisoner.”

In an interview with CNN, Melissa Mark-Viverito, the New York City Council Speaker who was among the officials who advocated for Rivera’s release, described the Puerto Rican terrorist’s liberation as historic.

Rivera had been imprisoned for an “unjust number of years,” argued Viverito, adding, “He is a political prisoner.”

The New York Daily News highlighted some of the atrocities affiliated with FALN.

“In 1974, the FALN began planting booby-trap bombs around New York. While most of these early explosions caused only property damage, the group’s clear intention was to kill and maim,” it reports. “In December 1974, an NYPD officer responding to a report of a dead body in an abandoned building on 110th St. was seriously injured by an FALN incendiary device.”

“In January 1975, a 10-pound dynamite bomb killed four people and injured dozens at Fraunces Tavern [in New York],” it adds. “The powerful blast was felt blocks away. In an eerie foreshadowing of 9/11, dust-covered victims staggered through downtown streets. The FALN quickly took responsibility for the deadly deed.”

The White House has acknowledged that Obama’s commutations are “unprecedented in the modern era.”

“While previous presidents have granted term commutations on a case-by-case basis — President Bill Clinton required [Rivera] a Puerto Rican nationalist convicted of seditious conspiracy to serve five more years, and President Richard Nixon made a Washington, D.C. murderer serve another decade — Obama appears to be the first to employ them as a matter of policy,” reported USA Today.