TUXTLA GUTIERREZ, Mexico (AP) - Police said on Wednesday they are investigating the recording and sale in local markets of a grisly video that shows a mob beating and burning to death three men suspected of raping and killing an Indian woman in southern Mexico.

A voice on the video says, "Gasoline on everything!" as the beaten suspects lie on the ground. Then the tape shows a man in flames, tied to a tree, writhing as he apparently burns.

One suspect is heard crying and pleading for mercy while voices in the background speak the Indian language of Tzotzil.

Tzotzil is spoken in the highlands of the southern state of Chiapas, where tapes of the attack were being sold in street markets for 15 to 20 pesos (S$1.46 to S$1.95) apiece.

The Chiapas state attorney general's office said all three men died. It is investigating both the mob attack and the sale of the video.

Voices on the tape allege the men were caught dumping the body of an Indian woman they raped and killed.

Mob violence against crime suspects is not infrequent in Chiapas, where small, remote villages often have little police presence.