Odebrecht has been at the center of one of the biggest transnational corruption scandals in Latin America's recent history. The firm is reported to have paid some $800 million (€698 million) in bribes to politicians in 10 different countries in exchange for government contracts.
Protesters gathered outside Martinez's office in Bogota, carrying flashlights to "shine a light" on what they called the country's corrupt institutions.
Demonstrations against Martinez also took place in Cali, Barranquilla, Bucaramanga and other cities, Colombian broadcaster Caracol reported.
Read more: Latin America: Outcry over corruption
Links to OdebrechtMartinez is currently in charge of investigating the firm's activities in Colombia, despite previously working as a legal adviser to one Odebrecht's Colombian partners.
Critics have said that Martinez is riddled with conflicts of interest due to his links to Odebrecht and that this makes him unsuitable for the job of chief prosecutor.
In 2015, Martinez berated an internal auditor over the phone for suggesting that Odebrecht was bribing politicians to secure a lucrative highway contract.
The recording of the call was revealed by a local news channel. In the recording, Martinez is heard screaming profanities at the auditor and urging him not to discuss his findings with anyone else.
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The auditor was later found dead in his home. Martinez has repeatedly denied any involvement in his death.
Protesters have been galvanized by the recent example of Peru's attorney general, Pedro Chavarry, who was also accused of hindering an investigation into Odebrecht and resigned.
jcg/amp (Reuters, AFP, AP)
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