GUATEMALA CITY (AFP) - Guatemalan Supreme Court Justice Cesar Barrientos, known for revoking dozens of death penalty sentences in a single year, committed suicide on Sunday, reportedly shooting himself in the head.

Relatives said the incident occurred as he rode in the back of his car with two bodyguards, in the south-western town of San Francisco Zapotitlan, according to local media.

"I confirm that he arrived (at the hospital) with a shot to the temple, but later died of the wound," fellow Justice Hector Manfredo Maldonado told the state-run Guatemalan News Agency, known as AGN.

In 2012, the Supreme Court's criminal chamber, led by chief justice Barrientos, revoked 53 death penalty sentences on the ground that they violated prisoners' "due process" and replaced them with 50-year prison sentences, the maximum allowed in the country.

The chief justice "spent most of his career working on justice issues and strengthening the Guatemalan legal framework, encouraging and directing major reforms in this sector," the US Embassy said in a Spanish-language statement.

Human rights activists also expressed their regrets.

Police and prosecutors are investigating the death.