Philippine police have identified the victim's live-in partner and her sibling as key suspects in the fatal shooting of American marine biologist Kent Carpenter inside his home in Sibulan, Negros Oriental.

Investigators noted inconsistencies in the woman's statements, including an initial claim of sexual assault that was not supported by forensic evidence.

Authorities are examining motives such as robbery or potential ties to Carpenter's research on coral reefs and marine biodiversity, which contributed to the Philippines' 2016 West Philippine Sea arbitration case.

The attack occurred late Sunday night when three men forced entry into Carpenter's residence, with one suspect shooting him in the head before fleeing.The woman's sibling is also under scrutiny due to frequent visits to the victim's home.