The brutal deaths of an Australian couple killed in the Philippines could be linked to a third woman, police have confirmed.

David Fisk, 57, and his de facto partner Lucita Cortez, 55, were found dead in a room with their hands and feet tied by cleaning staff at the Lake Hotel in Tagaytay city, south of Manila, about 1.35pm on Wednesday.

They were found next to the body of a third woman, Cortez’s 30-year-old daughter-in-law Mary Jane Cortez.

Local police are hunting down a man captured on CCTV hiding his face and entering a hotel room with a key card earlier in the morning. 

It’s believed the killer could be linked to Mary.

“We are looking at that option, that issue,” Tagaytay Police’s Jean Alagos exclusively told 9News.

Tagaytay police chief Charles Daven Capagcuan told the Associated Press that Fisk had his throat slit with a sharp object which may have caused his death while the Cortez women may have been suffocated using a pillow.

Ongoing autopsies would verify those initial indications, he said.

Fisk’s family, based in NSW’s Sutherland Shire, issued a statement saying they “pray for answers and the truth in this horrific matter”.

“The love we have for our father and Lucita is so dear and this situation is like living a nightmare,” the family said.

They asked for their privacy to be respected.

Capagcuan said the motive for the killings was not immediately clear and added some valuables of the victims, including their mobile phones, were not taken by the suspect.

“We were shocked by this incident,” Tagaytay Mayor Abraham Tolentino said, apologising to the families of the victims.

“We’re very sorry to our Australian friends. We will resolve this as soon as possible.”

Investigators were interviewing witnesses and examining security cameras at the hotel which could help identify the suspect or suspects, Tolentino said without elaborating.

Investigators were interviewing witnesses and examining security cameras at the hotel, including footage that showed a man wearing a mask and a hoodie and carrying a sling bag who walked out of the victims’ room a few hours before their bodies were discovered, Capagcuan said.

A Filipino relative of the Australian woman told the AP that the Australian couple flew from Sydney to the Indonesian resort island of Bali for a vacation then headed to the Philippines on Monday to visit her two children from a previous marriage in the country.

It’s understood the Australian couple had been due to fly back home to Sydney on July 13.

Tagaytay, about 60 kilometres south of Manila, is popular among local and foreign tourists who flock there for its cool weather and to view one of the world’s smallest active volcanos nestled in the middle of a lake.

Tolentino told the AP that the remains of the Australian man would be flown back to Sydney and the two women would be buried in the Philippines as requested by their relatives.

The government would pay for the women’s funeral and burial, he said.

A spokesman for the Department of Foreign Affairs and Trade said it was providing consular assistance to the families of the two Australians and expressed condolences to their families.

No other details were provided “owing to our privacy obligations”, the spokesperson said.