The victims, Tempo Dalangit, 64, and her son Salik, 28, died of multiple stab wounds.
Inspector Andrew Gomez, chief of police station 3 in Barangay Dalipuga, said the suspect, Kabib Saripada, 37, first attacked his mother and then turned to his brother.
Saripada later killed himself using the same knife.
Police could not confirm if Saripada was a drug user, but his neighbors in Barangay Dalipuga believe so. Lino de la Cruz