Mexico's National Human Rights Commission says it has concluded that 22 people were arbitrarily executed by federal police on a ranch in the western state of Michoacan last year.

Commission President Luis Raul Gonzalez Perez said Thursday the investigation revealed a range of human rights abuses on the part of government forces.

One police officer was killed in the confrontation on May 22, 2015. The government said the dead were drug cartel suspects who were hiding out on a ranch in Tanhuato near the border with Jalisco state.

The lopsided death toll of 42 to 1 had led to suspicions of extrajudicial killings.

The government refused to release the autopsy reports of the victims. The government's transparency watchdog earlier said there was no evidence to indicate human rights violations.