It was alleged that 70-year-old Nonarethi Maseti was found burnt to death at about 9am on Friday at her home in Nkanku location, Chafutweni village, Willowvale.
She was found by her grandson who had come to visited her, Captain Jackson Manatha said.
"The deceased was staying alone. The family of the deceased suspect that the house of the deceased was first doused with petrol before being set alight. The family members smelt petrol as they were the first to arrive at the scene. The motive for the arson is not known," he said.
Anyone with information about the arson was kindly requested to contact Willowvale police on 047-499-6200, or Crime Stop on 08600-10111.
Butterworth policing cluster commander Brigadier Trevor Mey condemned the attack on the elderly grandmother, as well as all attacks on women and children.