Mexican officials have formally apologized for the disappearance of a guerrilla sympathizer and folk singer who disappeared after being stopped at an army checkpoint in 1974.
Relatives of Rosendo Radilla say they chose not to attend the ceremony because the government hadn't consulted them about the date.
The Inter-American Court of Human Rights condemned Mexico's govenrment in 2009 for failing to adequately investigate the disappearance.
The court ordered the government to apologize, pay damages to relatives and investigate the case.
The Interior Department apologized Thursday, and authorities have carried out three unsuccessful attempts to find Radilla's remains at a former army base in the southern state of Guerrero.