Emma Lim, the prosecutions 27th witness against Estrada, is expected to corroborate the testimony of Carmencita Itchon, another Singson employee, that Estrada received millions of pesos collected by Singson from gambling bosses from all over the country.
Lim is now a director of the government-owned Camp John Hay-Poro Point Development Corp.
Itchon earlier testified that she had direct knowledge of the pay-offs to Estrada and his son, former San Juan Mayor Jinggoy Estrada, because she was the assistant of fugitive Yolanda Ricaforte, who was allegedly Estradas auditor on jueteng collections.
Itchon also claimed she received a monthly salary of P40,000 from Fontainbleau Inc., supposedly one of Estradas front companies, and that her immediate boss was the former president.
Government lawyers charged that Estrada and Jinggoy amassed ill-gotten wealth amounting to some P545 million.
Ombudsman Aniano Desierto said that after Lim, Singson himself will testify before the courts special division, chaired by Associate Justice Minita Chico-Nazario, which is handling the charges of plunder, illegal use of an alias and perjury against the former president.
Desierto said he pushed Singsons testimony ahead of schedule to hasten the courts ruling on Jinggoys petition for bail.
"We want to expedite the prosecution of this case," Desierto said.