Three brothers butchered their mother before eating her organs in a ritual killing, police have said.
Neighbours reported hearing strange noises coming from the family home for days before the body of Musala Amil, 56, was found in Ampatuan, Philippines.
Police discovered the badly mutilated body with several parts missing, drained of blood.
The sons ate parts of their mother raw, investigators said.
Brothers Dante, 35, Paroy, 21, and the youngest Ibrahim, 18, all deny killing their mother.
They said they had been trying to drive away an illness they believed was brought on by a bad spirit.
Officials investigating events leading to the gory discovery said the ritual killing happened last Wednesday.
Police are looking into reports the family had a history of mental disorders but are not ruling out the role of drug abuse in the killing.
Senior Inspector Ronald De Leon, Ampatuan Chief of Police, said the suspects will undergo drug tests.
The three men are of the Moro indigenous ethnic Muslim race.
All three suspects reside in a family farm at Purok Nabadtog in Barangay Kamasi in Ampatuan.
Community leaders said the three men killed their mother and feasted on parts of her body as if they were wild animals.
The village drew notoriety for the 2009 massacre of 58 people.