Jose Tomas Martinez Pinacho was a member and director of the FPR, Frente Popular Revolucionario, in the Sierra Sur area of Oaxaca.

He was also the founder of the Unión de Campesinos Pobres and was a vocal opponent of mining and mega infrastructure projects which would impact on the environment and the lives of peasant and indigenous communities.

On the morning of 24 August, 2020, Martinez Pinacho had been taking part in a protest in the state capital, Miahuatlán de Porfirio Díaz, to call for government funding for public services. After the protest Martinez Pinacho and a companion went to a local taqueria for lunch. As they were eating, heavily armed gunmen walked in and opened fire multiple times, killing Martinez Pinacho and injuring his companion, who has not been identified.

The killing of Martinez Pinacho was the latest in a series of attacks on and killings of community leaders and human rights defenders which have so far remained in impunity. A spokesperson for the FPR alleged the collusion of local officials and political bosses in the killings and said that the lack of progress in the case was indicative of an unwillingness to take effective action.

Sierra Sur is an isolated area suffering from high levels of violence driven by the conflict between criminal groups for control of illegal logging and hunting in the area.

Two people have been arrested in connection with the killing but there has been no progress in identifying the intellectual authors of the crime.