Desierto vowed to convince the Sandiganbayan to put Singson on the witness stand to once and for all complete the allegation that Estrada amassed millions from the illegal numbers game jueteng.
"Singson will be the coup de grace, the death blow on all the accused in the plunder case," said Desierto.
Estrada’s lawyers are scheduled to cross examine Singson’s personal secretary Emma Lim, who had claimed she collected millions of pesos from friends and relatives of the ousted leader and delivered them personally to him.
Desierto said he will move for the suspension of the cross examination and instead insist that Singson be presented as a new witness in the case.
"The prosecution will insist that Singson be heard immediately because he was already issued a subpoena," he said, adding that he expects Singson to be grilled by both the prosecution and the defense in three hours.
During the impeachment trial of Estrada, it was Singson who made the accusation that the president received P400 million in jueteng money from him in 21 months since he assumed office in July 1998.
Singson even called Estrada the "lord of all jueteng lords."
In his testimony at the separate investigations done by the two houses of Congress more than a year ago, Singson even said that Estrada used him as a "bagman" and negotiator with jueteng operators.
He said he collected a total of P545 million in jueteng proceeds since he was appointed bagman. The money, he said, came from Estrada’s close friend Charlie "Atong" Ang.
Singson detailed that of the P545 million, he delivered more than P400 million to Estrada every 15 days for 21 months, while the rest were kept in several bank accounts.
The Ilocos Sur governor also accused the former president of taking from him P130 million in tobacco excise taxes from his province. The money, according to him, came from the P200 million released by the Department of Budget and Management.
Singson’s testimony was backed up by a ledger which contained details on when the jueteng money were remitted to the president. The ledger, Singson said, was prepared by Estrada’s personal accountant, Yolanda Ricaforte.
The people he dragged into the case – such as Ang and Ricaforte – have all been charged of graft by the Ombudsman.
Meanwhile, Desierto said he will personally examine Equitable PCI Bank executive Clarissa Ocampo in connection with the illegal use of alias case against Estrada.
Ocampo accused Estrada of signing the fictitious name Jose Velarde in opening several accounts with Equitable PCI Bank.
Desierto said Ocampo will testify after Singson. He expects her to take the witness stand on Friday.
Desierto told The STAR that he is now awaiting the results of the preliminary investigation done by his men on Pineda, his brother Romy and former Undersecretary Anton Prieto, who once served as adviser to Estrada on Bicol affairs.
Singson’s employees Menchu Itchon and Emma Lim earlier told the Sandiganbayan that they collected millions of jueteng money from Pineda in his house in Greenhills, San Juan, and also from Prieto at a hotel in Makati.
Desierto said he just needs a probable cause against the Pineda brothers and Prieto for the filing of a separate plunder case against them.
"If there is strong evidence, we will file separate charges," he said.