Metro Manila (CNN Philippines, September 17) — The parents of hazing victim Horacio "Atio" Castillo III have asked the Vatican to look into how the University of Santo Tomas (UST) handled their son's case.

The couple told CNN Philippines their letter was received in late August.

"It's at the house of the Papal Nuncio," said Horacio Castillo, Jr.

"I would guess that the Vatican saw the flow of our theory with regards to the complaint," Carminia Castillo added. "I believe they will look at it. I believe that they will respond positively on our part."

Atio Castillo, a 22-year-old student at the Faculty of Civil Law, died on September 17, 2017 after hazing rites to the Aegis Juris fraternity. Ten initial suspects have been detained in Manila City Jail, but his family is still going after some alumni of the organization who were seen planning a cover-up to the crime in a Facebook chat room.

TIMELINE: The case of Horacio Castillo III

The Castillos first expressed their interest in raising the issue with the Vatican in February this year, as they are dissatisfied with how the school handled the killing. They are even aspiring for a papal audience.

UST is the only university in the Philippines to be conferred with a pontifical title, which means it is under the authority of the Vatican.

The couple suspect UST Law Dean Nilo Divina, who was a member of Aegis Juris, had a hand in the cover up. The dean maintains he was inactive in the organization, and pointed out he was not in the online chat room.

"I felt vindicated because my name was not at all mentioned in the exchange. I was not part of it," Divina told CNN Philippines.

"At the same time... I'm disappointed because of their reaction to [it]," he added, referring to some of his brothers' remarks in the online thread.

Divina also revealed he resigned quietly from the fraternity about six months ago.

The school maintains that it also condemned the hazing and the ten suspects have been expelled.

"We have always maintained that UST is not at fault. It has exercised the diligence required of it under the circumstances. We have banned hazing in all manner or form long before this incident," Divina said.

He added that the university suspended the accreditation of all fraternities and sororities indefinitely. He added that they also cooperated with the police and attended the Senate hearings on the hazing, which resulted in the passage of amendments to the Anti-Hazing Law.

"We'll basically explain our decision — that we have done all that we could under the circumstances," Divina said when asked how the school would react to a possible Vatican probe.

The Castillo family is determined not just to hold the school accountable, but the perpetrators as well. They will be filing criminal charges for obstruction of justice against the lawyers in the chat room.

"A lot of people are saying, 'Saan aabot 'to?' Sinasabi ko: We will never settle," said Mrs. Castillo. "We are here to defend our son... I'll see to it all of you will be brought to justice."