MANILA - Wearing "Justice for Kian" t-shirts, slain teen Kian delos Santos' family attended his final mass Saturday morning, accompanied by their loved ones, neighbors, and supporters.

Public Attorneys Office Chief Persida Acosta sat with them as they attended the funeral mass for the boy at the St. Francis of Assisi and Sta. Quiteria Parish in Caloocan City.

The boy's death has drawn public outrage against government's fierce war on drugs, as video evidence and witness statements suggest that he was executed.

PAO chief Persida Rueda Acosta sits with the Delos Santos family as final Mass for Kian begins. pic.twitter.com/PzAaFAHv96

— Patrick Quintos (@PatrickRQuintos) August 26, 2017

Kian's body arrives at the Sta. Quiteria Church. pic.twitter.com/88yKwErMpE

— Patrick Quintos (@PatrickRQuintos) August 26, 2017

Earlier, the funeral procession stopped in front of Caloocan City Police Station 7, where the officers linked to the teenager's Aug. 16 killing were assigned.

• PANOORIN: Labi ni Kian, papunta na sa simbahan

There, Kian's supporters offered a moment of prayer for drug war victims including the slain teenager, and also called for justice, holding aloft placards that read "Hustisya hindi bala (Justice not bullets)" and "Stop the killing, start the healing," among others.

Prayers offered as body of Kian stops by the police station where cops linked to the teenager's killing were assigned. pic.twitter.com/J8Mrn9X8RD

— Patrick Quintos (@PatrickRQuintos) August 26, 2017

ATM: A moment of prayer for drug war victims in front of Caloocan PCP 7 where cops in Kian's killing were assigned. pic.twitter.com/YbAKFEnO8m

— Patrick Quintos (@PatrickRQuintos) August 26, 2017

Security was strict during the funeral and procession, with local officials standing watch, along with security personnel from the Department of Justice's (DOJ) Witness Protection Program (WPP).

Acosta said Saturday morning that they applied for WPP security on Friday.

• BASAHIN: Mga magulang ni Kian, napangiti na: PAO chief

In an interview with radio DZMM, the WPP personnel said they were tasked by the DOJ to ensure the Delos Santos family's safety until the boy's burial at the La Loma Cemetery.

But "no further instruction" has been given to them, they said, adding that they will speak to the family after the teenager has been laid to rest. --with reports from Patrick Quintos and Arra Perez, ABS-CBN News