Two Japanese tourists were believed to have been murdered in the popular Philippine island resort of Coron in what police suspect to be a "yakuza" or gang killing.
Mr Masaru Itani, 59, and Mr Yoshihiro Arai, 24, were shot and killed as they were on a boat tour of the islets in the resort in Palawan province, one of the suspected accomplices told police.
Their bodies were then hacked to pieces and thrown into the sea.
Palawan's police chief, Superintendent Gabriel Lopez, said in a news conference on Monday that investigators were looking at insurance fraud as a possible motive, as the two victims were covered by multiple insurance policies.
He said the murders "had the character of a yakuza killing". Yakuza is the Japanese word for organised crime syndicates or gang members.
Police on Sunday filed multiple murder charges against six people, including 55-year-old Japanese businessman Hiroyuki Nagahama, who has been singled out by other suspects as the mastermind.
The authorities have also placed under custody two people who admitted to being part of a local gang called Commando Brotherhood and who allegedly witnessed the murder, including the operator of the boat that the victims had used for an island-hopping tour before Nagahama reported the men missing last Tuesday.
Investigations showed that Mr Itani, Mr Arai and Nagahama checked into GMG Hotel Coron on May 30.
They then hired a boat owned by local boat operator and Commando Brotherhood member Michael Suangco.
He told police that when the group reached the islet of West Galoc, Commando Brotherhood members grabbed Mr Itani and Mr Arai before shooting them in the head.
The gang then hacked the bodies to pieces and threw them into the sea en route to another Palawan resort, El Nido, he added.
"We threw them, piece by piece, into the water," he said, adding that Nagahama was the mastermind of the grisly plot.
Nagahama, who claimed he parted ways with the victims some time during the boat tour, has denied the allegations against him.
Palawan Governor Jose Alvarez told the Philippine Daily Inquirer that police found insurance documents among the victims' belongings. They were looking at money as a possible motive.