Stab wounds have been found on the burnt bodies of an elderly Japanese couple found dead Monday at their rental house in southern Bali, an Indonesian doctor said Tuesday.

Dudut Rustyadi, head of Sanglah General Hospital's forensic medicine department, said the wounds were found on the bodies of Norio Matsuba, 76, and Hiroko Matsuba, 73.

There were a number of puncture wounds on the man's back and his neck had been sliced. The woman had been stabbed in the neck and stomach, and there was rope around her neck and wrists.

Both had extensive posterior burn injuries and a pile of stacked firewood was found next to their bodies.

Rustyadi said autopsies would help to determine the cause of death.

Police Commissioner Aris Purwanto, head of the Denpasar Criminal Investigation Department, said autopsies would be performed after getting approval from family members.

Purwanto said the police have questioned six people, including the couple's adopted son who found their bodies, as well as their maid and driver.

"We still need to conduct further investigation," he said.

The burnt bodies of the couple were found in their second floor bedroom by their adopted son just before noon.

The house is located in a quiet residential area of Jimbaran, located south of Bali International Airport.

According to Japanese and others living in the neighborhood, the couple began living there about a year ago and the husband could often be seen walking a dog.

A 45-year-old woman friendly with the couple said, "They were very friendly and I never heard of any trouble."