Several Colombians have been arrested in connection with the murder of Fernando Villavicencio.
Pope Francis on Saturday strongly condemned the "unjustifiable" assassination of an Ecuadorian presidential candidate and urged all Ecuadorians to work together for peace.
History's first Latin American pope sent a telegram of condolence following the brazen assassination of Fernando Villavicencio at a political rally Wednesday in the capital Quito.
The killing of a figure whose life work was fighting crime and corruption has focused global attention on Ecuador's wave of violent deaths and the country's vulnerability to criminality.
The pope, an Argentine Jesuit who visited Ecuador in 2015 in one of the first trips of his pontificate, said he was praying for Villavicencio's family and all Ecuador's people.
"Likewise, in the face of the suffering caused by unjustifiable violence, which he condemns with all his forces, His Holiness calls on all citizens and political forces to join in a common effort in favour of peace," said the telegram, which was signed by the Vatican secretary of state.
Ecuador has detained six Colombian men in connection with the slaying.
In his final speech as a candidate for the presidency, Villavicencio promised to continue his work combating Ecuador's law and order problems, telling a crowd he would lock up "thieves" responsible for a culture of entrenched corruption.
He had previously said he was the target of death threats from multiple parties, including one of the largest Mexican drug cartels.
In a statement shortly before he died, he said: “Here I am showing my face. I'm not scared of them."