His precise date of death is unknown as he was extrajudicially executed along with several other FRELIMO dissidents and his wife, Celina[2] by the post-independence government of Samora Machel.

In April 1970, Simango left for Egypt where, with other dissidents like Paulo Gumane, FRELIMO's founding Deputy General Secretary, he became a leader of COREMO, another small liberation movement.

Neither the place of burial nor manner of their executions have ever been disclosed by the authorities, though scholar Phillip Rothwell believes Simango was killed in October 1979 and speculates his death was to prevent him from being used as a figurehead by other rebel groups such as RENAMO.

On his return to Mozambique in 1974, according to his biographer Nkomo, Simango held tentative talks as leader of the PCN with white settler parties in a bid to garner strategic support against one-party rule.

This presaged a settlement like that negotiated five years later in the Lancaster House Agreement for multi-party elections in Zimbabwe but, in 1974, it was viewed as treasonous by FRELIMO hardliners.