Metro Manila (CNN Philippines, September 7) — President Rodrigo Duterte promised to resign if allegations that he and his family are involved in corruption would be proven true.

His son, Vice Mayor Paolo Duterte, is accused of peddling influence at the Bureau of Customs (BOC) to let shipments through, for a fee.

The controversy began with customs fixer, Mark Taguba, testifying on the "tara" or bribery system at Customs, and revealing the Davao Group's operations within the BOC. If true, it exposes how corruption lie deep in the beleaguered agency, and how high up it could go.

Who are the members of the Davao Group? Transcripts of the series of Senate hearings show a cast of aliases.

Based on Taguba's testimony at the Senate Blue Ribbon Committe, a certain 'Jojo' at the BOC introduced him to the group, and asked for an "enrollment fee" of P5 million.

Customs officials said they could not identify the 'Jojo' Taguba was pertaining to because there are many namesakes in the bureau.

Taguba said the Davao Group is composed of "Tita Nanie, Jack, and Small," including a certain "vice mayor."

When pressed to name the vice mayor, the witness said: "I think it's Paolo...Duterte."

He, however, said it was hearsay, as the three merely made a claim that they had enough backing: "Malakas ako ngayon sa Customs kasi dahil kay Vice Mayor ako."

(Translation: We have enough backing at Customs because of the vice mayor.)

Taguba said he usually transacted with Tita Nanie, and often paid her off.

On Jan. 11, Taguba said Tita Nanie sent him this text: "Good am, Mark, we'll make final arrangement with Jack. He is the handler of Paolo. Now, we have to advance the enroll - he can fly down to Davao to arrange your meeting with Polong ASAP. During the meeting, you personally turn over the five million, same manner you likewise turn over the LMLN (1 million) to Jack when we meet."

Tita Nanie also told him in a text that Jack is the handler of Paolo Duterte.

Taguba said they were to be flown to Davao, and will stay at the Marco Polo Hotel. When they got there, supposedly on Jan. 16 at noon, Jack brought him to a seafood restaurant where they met with Small, who was later identified as Davao City Councilor Nilo 'Small' Abellera.

Taguba said Abellera is known to be close to Paolo.

The witness said he gave the money to Small, in a blue Lacoste bag.

Small also allegedly asked for a weekly remittance, for each box of shipment. He said the money would be given to Jack, who would fly to Manila every Friday to collect the fee from Taguba.

The fee was set at P10,000 per container. With an average of 100 containers per week, that's about P1 million a week in payoffs.

Abellera told Taguba that Paolo was having second thoughts transacting with him, but that he needed to only give P2 million more to convince the vice mayor otherwise.

Taguba said Abellera told him: "Kung tatanggapin ka namin sa grupo namin, kailangan mag-remit ka nang tama."

(Translation: If you're to join our group, you have to remit properly.)

Taguba said he gave P2 million to Jack, who would give the money to Paolo. Taguba said he never met the president's son.

In all, he said he gave the Davao Group P8 million.

On March 17, Taguba again said he had a series of text exchanges with Tita Nanie.

One text read, "Tita, there's no need to panic. I haven't filed it yet. All I need from Tito Jack is for either P or Mance to call collector Jet Maronilla that we have go signal for our SPL."

Taguba said "P or Mance" were Paolo Duterte and Mans Carpio, who could let his "SPL" or special container through.

During the Aug. 31 hearing, Abellera finally appeared before the Senate, and denied belonging to Davao Group.

He, however, admitted meeting Taguba and Jack at a resto bar, Casa de Amigos, in Davao.

He said Jack, someone whom he once gave his calling card to but did not know personally, wanted to introduce a customs broker who wanted to meet Paolo. He said he could not make such an arrangement, and that the meeting lasted 10 minutes and no bribe money was given.

"Knowing that the vice mayor does not involve himself with such matters, I politely told Jack that I could not arrange such meeting," he said. Abellera also denied knowing Tita Nanie.

Early in the hearings, Taguba requested for an executive session so he would not have to name people in public.

After his expose, he issued a statement apologizing to Vice Mayor Duterte and the first family, and reiterated that the involvement of the two to the bribery system at Customs was "hearsay in nature."

"I wish to categorically make it clear that: 1. I had never testified, nor will I ever testify that Vice Mayor Paolo Duterte and/or Atty. Manse Carpio were involved in the shipment of illegal drugs into the country. Neither have I testified, nor will I ever testify that the aforementioned individuals were involved in the 'Tara System' that was in place at the Bureau of Customs," he said.

Trillanes then said Taguba was pressured to issue the apology and denial.

Vice Mayor Duterte, in a statement on Aug. 8, denied the accusations and said he would not even "dignify lies with a response."

"Taguba admitted that his testimony against me was based entirely on rumors. Why would we entertain or believe a hearsay," he said.