A governmental human rights agency is investigating why about 150 bodies of crime victims were dumped in pits in the central Mexican state of Morelos.

Some of the bodies may have been buried in the mass common graves simply to clean out a state morgue. But some of the bodies lacked the case file markers they are supposed to be buried with, leading to questions about how they died.

The Morelos state human rights commission said it began an investigation Friday with a visual inspection of the grave site.

Commission spokesman Rafael Idiaquez said the case came to light when the family of one victim demanded his body for burial, but was told it had already been interred.