The initial hypothesis of Colombia’s air force and civil aviation investigators is that that plane crashed due to engine failure, according to the minister.

However, according to the Conservative Party, the plane was on its way to pick up four prominent politicians, including former President Andres Pastrana, at the Guaymaral airport, a private airport in the north of the capital.

Crashed plane in Bogota was picking up Conservative Party leadership

Conservatives have even implied the crash could have been the result of an attack, rather than a mechanical failure.

Pastrana, a fierce critic of an ongoing peace process with leftist FARC guerrillas, asked President Juan Manuel Santos on Twitter whether a “national and international” investigation of the crash would be conducted “before evidence disappears.”

In his response, the defense minister said he will ask the NTSB to assign an investigator to determine what caused the plane to go down outside Bogota.

Additionally, Villegas said he hoped to enlist the involvement of American military aircraft manufacturer Beechcraft and US-based Lycoming, the maker of the plane’s engine, in the investigation.

Besides Pastrana, the three other politicians supposed to board the plane included former presidential candidate Marta Lucia Ramirez, ex-Peace Commissioner Camilo Gomez and the vice president of the party, Angela Ospina.