The Colombian Attorney General's Office released evidence on Thursday of irregularities and corruption in the March legislative elections, involving six congressmen.
During a press conference, Attorney General Nestor Humberto Martinez said a criminal network involved in vote buying had been discovered, after 50 investigators analyzed several thousand hours of recorded video and audio.
According to Martinez, the criminal organization offers "services" to various political campaigns for bribes, buy votes, and threaten public servants into voting for particular candidates.
There is also evidence that this network has operated in previous elections, notably those of 2015.
An investigation has now been opened into elected senators Margarita Restrepo, Fabian Castillo, Lilbeth Llinas, Julian Besoya and Maria Fernanda Cabal for vote buying.
A contractor in the Bogota mayor's office is also being investigated for threatening voters into choosing candidates for the Centro Democratico party of Ivan Duque, who won the presidential election.