From the very start, national police chief Gen. Jose Melencio C. Nartatez, Jr. never doubted the capability of local investigators to solve the July 12 killing of an American marine biologist in Negros Oriental.

And three days later, his confidence was vindicated with the arrest of three of the four suspects in the death of the 73-year old Kent Carpenter who was at the forefront of marine ecosystem protection in the country.

“The swift arrest of three suspects reflects the dedication and professionalism of our investigators. But our work is far from over. Our priority is to complete the case by arresting the remaining suspect, ensuring all evidence is properly documented, and building a strong case that will secure the conviction of everyone responsible,” Nartatez said.

Nartatez lauded the investigation and operating teams for the arrest of two of the suspects that later forced the third suspect to surrender. A manhunt is ongoing for the fourth suspect who allegedly carted away the group’s loot in a possible case of robbery gone wrong.

Based on the investigation, the suspects allegedly entered Carpenter's home in Sibulan, Negros Oriental on July 12. Authorities said the evidence gathered so far points to a robbery that turned deadly.

One of the suspects had previously worked at the victims' residence and allegedly used that opportunity to observe the property before the crime. Police are also determining whether the suspects were involved in previous robbery incidents in the area.

Police also said there is no indication at this stage that the crime was connected to Carpenter's work as a marine biologist or his reported role in the Philippines' 2016 South China Sea arbitral victory.

“I have directed all concerned units to sustain intensified manhunt operations until the remaining suspect is arrested,” Nartatez said.

“We are maximizing intelligence gathering, coordinating closely with neighboring police units, and encouraging the public to provide any information that can lead to his immediate capture. We will not stop until every person involved in this crime is brought before the courts,” he added.

The three arrested suspects are facing robbery with homicide charges while authorities are conducting further forensic examination of the alleged sexual assault on Carpenter’s live-in partner.

The PNP appealed to the public to cooperate with authorities by reporting any information that could lead to the immediate arrest of the remaining suspect.