The former two-term Colombian president Álvaro Uribe Vélez announced Tuesday evening that he was giving up his seat in Congress, after the President of the Supreme Court (CSJ) José Luis Barceló summoned the senator of Centro Democrático party as part of a criminal investigation involving bribery and witness tampering.

Four days after the new Congress was sworn-in on July 20, the right-wing former President, who governed from 2002-2010, announced on Twitter that he was “morally impeded to be a senator,” and in order to take charge of his defense was giving up his seat. Hours after Uribe’s announcement, the political heavyweights of the party founded by the conservative politician gathered in Bogotá to draft an official statement in support of a leader who counts with a large and loyal base of support.

President-elect Iván Duque, who will be sworn into office August 7, told the media that Uribe’s “honorability and innocence will prevail.” Duque was the official candidate of Centro Democrático during the 2018 presidential election campaign and clinched victory with more than 10 million votes.

The criminal investigation that involves Álvaro Uribe also implicates his brother Santiago. The investigation was formally opened by the magistrate of the country’s highest court after a former paramilitary commander, Guillermo Monsalve claims lawyers representing Álvaro Uribe attempted to bribe him in order to retract his version of homicides that may have taken place on the property of the Guacharacas hacienda, owned of the Uribe Vélez family.

Monsalve is currently detained in La Picota maximum security prison on the outskirts of Bogotá on multiple charges, including homicide and extortion.

Allegations of witness tampering date back to 2011 when leftist senator Iván Cepeda contacted the former paramilitary in order to demonstrate to Congress the responsibility of Uribe Vélez in organizing death squads when he was governor of Antioquia (1995-1997).

As a result of Monsalve’s testimony, the General Prosecutor’s Office requested the Supreme Court grant the prisoner special protection as a key witness. In a recorded interview with Cepeda, the former commander of the Metro Bloc states that “Álvaro Uribe coordinated with the military” operations that led to massacres in Eastern Antioquia, and Santiago was a “member” of the criminal organization.

After Monsalve allegedly claimed to have been coerced by Uribe’s legal team, the Supreme Court’s Barceló officially demanded that all videos that captured the entrance of the lawyers to La Pictota be seized as evidence. But, according to a report in La Nueva Prensa, the footage disappeared. However, when the magistrate made the same request to the headquarters of the National Penitentiary Institute (INPEC), he managed to obtain authentic copies.

The former president’s involvement in a criminal case could expand to include two other key witnesses who oversaw paramilitary operations in Antioquia – Gabriel Muñoz Ramírez and Ramiro de Jesús Henao Aguilar.

Muñoz Ramírez is accused of 500 homicides as a member of the Metro Bloc, whose territory included the Guacharacas estate. Henao Aguilar commanded the Batalla de Santuario front, which orchestrated massacres in the Oriente Antioqueño between 1996 and 2003 when the group demobilized.

Uribe Vélez insists he is the victim of a “set-up” and that the highest court has refused to hear his version. “I have never eluded the Supreme Court, so that they can now invent that my resignation as a Senator is to take away their competence,” said Uribe in a statement.

As of Wednesday evening, the senator and ex-president hadn’t presented his letter of resignation to Congress.