Ifugao police gathered the "evidence" from the crime scene and from the house of principal suspect Juan Dontugan in Batad near the world-renowned Banaue rice terraces.
Police hope the results of the analysis will help them build a strong case against the attacker or attackers of Campbell.
The remains of the Peace Corps volunteer were found in a shallow grave 10 days after she was last seen alive on Easter Sunday. Initial autopsy results showed she was bludgeoned to death.
Submitted recently for laboratory examination were two red empty tin cans of sardines, an empty green cigarette pack, a plastic bottle of sunblock lotion, a makeup kit, a piece of crumpled paper, a digital camera placed in a synthetic camera bag, an empty bottle of mineral water without cover, and two pairs of eyeglasses, one of which was damaged.
Also retrieved from the crime scene were a lady’s white underwear, a cotton bud, a sanitary napkin, and a piece of greenish cloth.
Earlier gathered from Dontugan’s house were a wooden pestle with what appeared to be bloodstains, two pairs of bloodied denim pants, a black baseball cap with the marking "June," and what looked like sputum in a brown envelop.
Police earlier made public a photograph of Dontugan but stressed that more pieces of evidence were needed to pin him down for the crime.
"We have to strengthen the case because all we have are circumstantial evidence. We have to find direct evidence against him to warrant the filing of charges in court," Cordillera Regional Police director Chief Superintendent Raul Gonzales said.
As they await the results of the autopsy on Campbell, police have renewed their call for Dontugan to surface and prove his innocence.
Chief Supt. Samuel Pagdilao, PNP spokesman, said the suspect should present himself to authorities if he wanted to clear his name.
"If he has nothing to hide, then he should come forward and clear his name," Pagdilao said.
He also said that more than one suspect might be involved in the crime because two pairs of bloodied jeans were found. – With Christina Mendez, James Mananghaya