A journalist at three newspapers shut down by the government, Marques exposes the slaughter of his countrymen, the plundering of the country's wealth, and the corruption of its regime.

Marquez began working at the only newspaper in Angola in 1991, the year of the country’s first democratic elections. In 1999 he was imprisoned for 40 days without charges after he held the President responsible "for the destruction of the country" and "accountable for the promotion of incompetence, embezzlement, and corruption."

The publicity surrounding the case generated an unprecedented attention from humanitarian groups worldwide. The UN Human Rights Committee ruled that Angola had violated the freedom of expression of a journalist and a called for broad liberalization of the Angolan regime.

Marquez has written extensively about the malfeasance of the government and foreign interests in oil-rich Cabinda Province and the plundering of diamonds from the Lunda Provinces and highlighted the suffering of the people of the regions.

In addition to his reporting, he produced four human rights reports on Angola.

Marques organized religious and civic leaders who stimulated the first public, independent discussion of the brutal civil war that raged for 30 years before and after Angola’s independence from Portugal. They took their call for a ceasefire to Lisbon and the European Parliament.

In 2000, the National Association of Black Journalists of the United States presented Marques with the Percy Qoboza Award for Outstanding Courage, while the European Parliament bestowed upon him the Freedom Passport.