Police are still searching for two brothers allegedly involved in the robbery-slay of American marine biologist Dr. Kent Carpenter in Sibulan, Negros Oriental, although the Philippine National Police (PNP) now considers the case solved but not yet closed.

Speaking at a press briefing in Camp Crame on Monday, PNP spokesperson Col. Allen Rae Co said investigators identified the brother of fugitive suspect alias "Eden" as one of those involved in the fatal shooting of Carpenter at his residence in Barangay Ajong on 12 July.

Co said four of the six identified suspects are already under police custody and have undergone inquest proceedings, while charges against the two remaining fugitives will be filed through regular proceedings before the prosecutor's office.

"We now have six suspects in the Carpenter case. The first two were arrested, two surrendered, and now alias Eden and his brother have also been identified as participants. The four have undergone inquest, while cases against the remaining two will be filed through regular filing before the prosecutor's office," Co said.

He explained that the case is already considered solved because suspects have been identified and four have been arrested.

"Once we have identified the suspects and filed a case, it is considered cleared. Once at least one or more suspects are arrested, and in this case we already have four in custody, the case is considered solved," he added.

Despite the identification of additional suspects, Co said robbery remains the primary motive behind Carpenter's killing.

"Wala pa tayong nakikitang indikasyon na iba ang motibo. Kung ang tinutukoy ay may kaugnayan sa kanyang trabaho, wala pa tayong nakikitang ganoon. Pero patuloy pa rin ang ating imbestigasyon. Hindi ibig sabihin na nakilala na natin ang mga suspek at nakapagsampa na ng kaso ay tapos na ito," he said.