Dexter Carlos whispers his last words to his daughter at her funeral in Bulacan on Wednesday. Carlos' wife, along with their 3 children and his mother-in-law, were brutally killed in their house in Bulacan three weeks ago. Jonathan Cellona, ABS-CBN News

MANILA - Public Attorney's Office (PAO) chief Persida Rueda-Acosta has questioned the motive of investigating officers in Bulacan who included the father of a massacred family in their probe.

Acosta said cops investigating the murder of Dexter Carlos' family in San Jose Del Monte Bulacan had two full weeks to verify information from the widower.

"Why only now after two weeks saka nila ide-declare na person of interest? Kasa-kasama pa nila araw-araw 'yan nang nagkakalap ng ebidensiya," she told DZMM Thursday.

Carlos, a security guard, earlier said he found his lifeless wife, 3 children, and mother-in-law when he got home from graveyard duty last June 27.

Rueda-Acosta said the Department of Justice already placed Carlos in the witness protection program. Even President Rodrigo Duterte visited him and vowed justice, she added.

"Sabi ho sa akin ni Dexter, 'attorney, saan na ako tatakbo para humingi ng tulong ngayon, bakit ngayon ako ang tinuturing diumano ng mga pulis na suspect?'" she said.

The PAO chief said she believes Carlos, who's been traumatized by the tragedy, is innocent and should not be treated as a person of interest by police investigators.

CCTV footage from a bank, the lawyer added, would show that Carlos was on guard duty on the night his family was murdered at home.

Investigators previously announced that they will invite Carlos to shed light on some unusual features of the crime scene, including the lack of bloodstains in certain parts of the victims' house.

"Papaano natin masasabi na si Mr. Carlos ay walang kinalaman sa krimen kung hindi natin ma-establish ang kinaroroonan niya, anong ginagawa niya noong nangyari ang krimen," said Bulacan police chief Senior Supt. Romeo Caramat.

A construction worker, identified as Carmelino Ibañez, has already confessed to murdering the victims and raping 2 women while high on drugs. He also namedropped two other accomplices.

However, Ibañez later retracted his statement and said he was tortured and threatened by cops to own up to the murders. Three persons of interests have also died in supposed vigilante attacks.