Families of 43 college students missing in southern Mexico since September say desperation and a lack of confidence in the government has driven them to appeal to the leader of a drug gang for help in locating their sons.

After months of investigation, Mexican officials concluded a different drug gang murdered and incinerated the young men. But six months after the disappearance, and with only one of the missing identified through a bone fragment, parents are asking the leader of a rival gang to share what he knows.

A sign hung near the city where the students disappeared asks the purported leader of Los Rojos gang to "help us find our sons."

The father of a missing student says the families have not had a response as of Wednesday afternoon.