In an interview with reporters, Aquino said Mupas used a very strict standard of proof in looking for corroborative evidence proving Mrs. Arroyo ordered Maguindanao Governor Andal Ampatuan Sr. to rig the 2007 elections.
Aquino said it is "impossible" to obtain such corroborative evidence since there is no other witness to the alleged instruction of Mrs. Arroyo to Ampatuan other than former Maguindanao provincial administrator Norie Unas.
"Alangan naman nating isipin na magbibigay ng testimonya 'yung dalawa laban sa sarili nila. So pwede nang testigo 'yung isa. Paano kaya tayo magkakaroon ng corroborative, 'yung makaka-susuog, makakasang-ayon doon sa binanggit na pag-uusap nitong dalawa? So medyo ang taas naman yata ng test na parang imposible na ma-attain dahil wala nang ibang nakarinig ng kanilang usapan doon sa issue ng electoral faud," the President said.
Aquino is waiting for the decision of the Sandiganbayan on whether it would issue a warrant of arrest against Mrs. Arroyo who was charged with plunder over the alleged misuse of PCSO funds.
Plunder is a non-bailable offense.
"Meron pang case pending before the Sandiganbayan, plunder. And plunder is non-bailable also. So hinihintay natin 'yung decision ng Sandiganbayan," he said.