Van Niekerk, a former editor of the Johannesburg Mail & Guardian and a staff writer at the Washington-based International Consortium of Investigative Journalists, has frequently reported from Mozambique, where he befriended Cardoso in the early 1990s.
Van Niekerk was part of a CPJ delegation that visited the capital, Maputo, in June 2001 to learn more about the state's investigation into the Cardoso murder. Cardoso was gunned down on November 22, 2000.
Mozambican state prosecutors contend he was killed for aggressively covering a 1996 banking fraud at the government-controlled Commercial Bank of Mozambique in his now defunct business daily, Metical.
Six men, arrested in March 2001, are standing trial for conspiring to murder Cardoso. One of them escaped from Maputo's maximum-security prison in September 2002 after prison guards said they received "orders from above." He is being tried in absentia.
Most of the remaining five have confessed their part in the assassination and have accused Nymphine Chissano, a son of President Joaquim Chissano, of ordering the killing. Chissano has denied any involvement.
Law enforcement officials recently announced that a separate case file was opened listing Chissano as a suspect.
For more information, read The Case of Carlos Cardoso, CPJ's special coverage of the events in Mozambique.