A group of elite Mozambican policemen have been implicated in the shooting of a prominent poll observer just days ahead of elections.
Anastacio Matavel was shot dead as he left an election training session in the southern Gaza province on Monday.
Five men armed with assault rifles shot Mr Matavel 10 times before fleeing in a car, which crashed during their getaway.
Two died in the crash, one was arrested and two remain at large, police said.
Four of the five men in the car were members of an elite police unit, known as the Rapid Intervention Force, authorities said.
Police have launched an investigation into the killing, which has heightened tensions ahead of next Tuesday's presidential and parliamentary elections.
Human Rights Watch described Mr Matavel's killing as "a chilling development that casts a dark shadow over the Mozambican elections".
The group said serious abuses and acts of violence have been documented in Gaza province since the start of the election campaign on 31 August.
Killing of a leading election observer this morning, 8 days to the voting day, is the latest of many incidents since the start of the campaign. Silence of the Electoral Commission and the inability of the police to stop it, are fueling the violence & impunity #MozambiqueElections pic.twitter.com/AjGCJ5Xfse— Zenaida Machado (@zenaidamz) October 7, 2019
Mozambique, which gained independence from Portugal in 1975, is still suffering from the effects of a 16-year civil war that ended in 1992.
Tensions remain between the ruling Frelimo party and the opposition former rebel movement Renamo, despite the signing of an historic ceasefire agreement in August.
In the presidential election, Frelimo's incumbent President Filipe Nyusi is vying for a second five-year term against Renamo's Ossufo Momade.
Pictures of Mr Matavel's funeral, held in the city of Xai-Xai, have been posted to Facebook by Sala da Paz, a group that monitors election-related violence.
At his funeral on Wednesday, religious leaders condemned his shooting as the "spirit of tyranny" and called for an end to the violence.
The mayor of Xai-Xai said he felt "profound revulsion at the macabre act" and demanded an investigation into "this unprecedented crime".
The European Union's election observer mission has led international condemnation of the murder.
"These elections are fundamental for the successful implementation of the peace process and for Mozambique's long-term stability and prosperity," it said in a statement.