A Peace Corps helicopter had joined the search, according to Superintendent Joseph Adnol, CAR police spokesman.
Philippine National Police chief Director General Oscar Calderon has directed CAR police commander Chief Superintendent Raul Gonzales to activate the region’s Crisis Management Committee to ensure coordinated police and civilian search and rescue efforts.
Calderon said the PNP is closely coordinating with the US Embassy in Manila on the progress of the search for Campbell.
Adnol said there is no indication yet that New People’s Army (NPA) rebels were behind Campbell’s disappearance.
"We are looking into possible accident or crime angle," he said.
Adnol said the Ifugao Police’s Provincial Mobile Groups have fanned out to several barangays in Batad, Ifugao where Campbell was last seen.
"The result of search and rescue is negative," he said. "They have scoured the possible places where she had gone and the persons she had contacted."
Campbell went missing on the afternoon of April 8 when she embarked alone on a hiking trip.
Meanwhile, Calderon alerted all police regional offices to closely monitor the activities of local and foreign tourists, especially during the summer vacation season when tourist arrival is at its peak.
Calderon is also closely monitoring the progress of investigation into a robbery-slay case in Bohol where German couple Helmut and Eutiquia Malinka were killed.
Central Visayas police director Chief Superintendent Silverio Alarcio reported that the couple’s maid, Virginia Salota, has been interviewed by investigators to shed light on the killing.
Salota was merely hogtied and left unharmed by the two robbers, who barged inside the couple’s house, he added.