The bodies of David Fisk, 57, Lucita Cortez, 55, and her daughter-in-law Mary Jane Cortez, 30, were found by cleaning staff last Wednesday at Lake Hotel in Tagaytay.
The bodies had their hands and feet tied.
CCTV had shown a male suspected to be involved with their deaths, leaving and re-entering the trio’s shared room.
He was wearing a mask and a hoodie and carrying a sling bag.
Now, a man has handed himself in to local police, local officials confirmed.
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.
Police had previously said it was possible the killer was linked to Mary Jane Cortez.
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.
It’s understood the Australian couple had been on an overseas trip and were due to fly home on July 13.