MANILA- Senator Risa Hontiveros on Thursday defended her office's custody of the witnesses in the killing of 17-year-old Kian Loyd Delos Santos.

Hotiveros said she took custody of the witnesses who are minors at the request of their families and even the Delos Santos family due to threats they have been receiving.

"Sa simula pa lang, when my office took custody of the witnesses, it was in response to the request of these witnesses and their families, and even the family of Kian to protect them from the threats that they have been receiving," she said in a statement.

She clarified that guardians of the witnesses have also signed consent forms. She noted that she will respect the decision of the families if they decide to transfer the custody of the witnesses to others.

"Sa dulo, ang ultimong desisyon ay nasa mga witnesses at kanilang pamilya," she said.

A grade 11 student, Delos Santos' shooting on August 16 has prompted public outrage amid evidence suggesting that the boy was executed.

CCTV footage showed police dragging Delos Santos to the spot where he was later shot dead. Witnesses also said that before the boy was killed, police gave him a gun and told him to run for his life.

• Binatilyo, patay nang 'manlaban' sa pulis; pero iba ang kuha sa CCTV

Two of three officers implicated in the killing have since admitted that it was them who were captured in the CCTV footage dragging Delos Santos, according to the Philippine National Police - Internal Affairs Service.

• Cops admit CCTV showed Kian being dragged: IAS

The Caloocan City police have said that Delos Santos was a drug runner for his father and uncle, an allegation that the boy’s family denied. The police also presented a witness, Renato “Nono” Loveras, who allegedly did transactions with the boy.

• 'Katransaksyon sa droga' ni Kian, inilabas ng PNP

Both Justice Chief Vitaliano Aguirre II and Public Attorney's Office chief Persida Acosta pointed out that Hontiveros has no power to take custody of the witnesses in Delos Santos' killing.

The witnesses should be placed under the Philippine National Police or the Witness Protection Program of the National Bureau of Investigation (NBI), they said.

"Ako lamang ay nagugulat sa biglang pangyayari. Mukhang may mga pwersang gumagalaw para kunin ang mga testigo, i-undermine ang kaso at limitahan ang accountability sa panig lamang ng mga pulis," Hontiveros said.

Hontiveros also hit back at Aguirre's statement that the death of the teen has been "blown out of proportion."

• Aguirre: 11th grader's death 'blown out of proportion'

"Kayo ba, ipagkakatiwala ninyo ang buhay n'yo o ng inyong mga anak kay Secretary Aguirre, na siyang nag-downgrade ng kaso ng mga pulis na pumaslang kay Albuera Mayor Espinosa? Na mas naniniwala sa testimonies ng mga bilanggong drug lords kaysa sa mga batang testigo?" she said.

The Senate is conducting an inquiry into Delos Santos' killing.