An international advocacy group is calling for an investigation into the mysterious slaying of a Haitian activist and his wife.

Amnesty International said Wednesday that Haitian human rights groups fear the killing could have been political because of the violent nature of the slaying and the senior position of the activist.

Police say Daniel Dorsinvil and Girldy Lareche were killed Saturday by a lone gunman as they walked through a residential neighborhood in the capital, Port-au-Prince. Police didn't give a motive for the killing.

Human rights groups say Dorsinvil was shot in the heart and Lareche was shot five times.

Dorsinvil was coordinator for the Platform of Haitian Human Rights Organizations.

Haitian human rights lawyers have said they are being targeted for their work lately.