But Manapat is nowhere to be found, with his lawyer clueless as to his clients whereabouts.
National Archives employees Vicelyn Tarin, Remmel Talabis and Emman Llamera have accused Manapat of ordering them to forge documents to show that Poe is not a natural-born Filipino citizen.
In a two-page order, Chairman Dario Rama of the Presidential Anti-Graft Commission said the 10-day period is "non extendible," and that there was "sufficient basis" to file an administrative case against Manapat.
"Failure on your part to file your counter-affidavit or verified answer within the given period shall be construed as a waiver on your part to be heard and to adduce evidence in your behalf," read the order.
Rama also warned Manapat against filing a motion to dismiss or a motion for a bill of particulars.
The Sandiganbayan may also order Manapats arrest if he fails to explain within 10 days why he did not attend a Feb. 16 hearing on graft charges filed against him by the three employees of the National Archives.
Acting Presiding Justice Edilberto Sandoval ordered Manapats lawyer, Jose Jose, to explain why his clients P30,000 bail should not be canceled and a warrant issued for his arrest.
However, Jose told reporters he has not seen Manapat since he went on leave following charges that he forged Poes birth records.
"I was hoping to see him today," he said. "Hindi ko nga alam kung ano ang gagawin ko."
The Office of the Ombudsman is also investigating allegations that Manapat tampered documents on file at the National Archives to make it appear that Poe is not a Filipino citizen, and that his father, Allan Fernando Poe was a Spaniard, who had married a certain Paulita Gomez in 1936.
Poe plans to sue Manapat for falsifying documents pertaining to the birth and marriage records of his father.
Sen. Vicente Sotto III, Poes spokesman, said that before he went on leave of absence, Manapat had taken out from the National Archives several computer files allegedly containing forged birth and marriage certificates of Allan Fernando Poe, and a supposed bigamy complaint of Gomez.
"The removal of the CPU was done without the consent of the National Archives property office," he said. "Director Manapat, who took it out himself, is therefore liable to infidelity and even theft, among other charges."
Earlier, Presidential Spokesman Ignacio Bunye said Manapat will remain on leave until he has cleared himself of charges that he forged documents related to Poes citizenship and other allegations of irregularities against him.
President Arroyo has named Marietta Chou as officer-in-charge of the National Archives in the absence of Manapat.
Sotto said Manapat probably wanted to erase the files which contain copies of the documents he had allegedly ordered forged.
"Manapats pulling out of the CPU of the computer in his office is crucial to the investigations into the involvement of Manapat in the forging of documents presented by lawyer Victorino Fornier (to seek Poes disqualification from the May 10 presidential elections)," he said.
"Removing them compromises the investigation, and can even be considered as an attempt to tamper with evidence."
Sotto said Manapat did not realize that the files in the CPU, which he had taken, were also stored in other computers as they were saved in a shared folder.
A shared folder can be opened through any computer connected in a network to other workstations, he added.
During a Senate hearing, Tarin, Talabis and Llamera said Manapat ordered them to scan pre-World War II birth certificates and marriage contracts and to change pertinent data with the use of computers to make it appear that Allan Fernando Poe was married to a certain Paulita Gomez.
Among the documents supposedly forged were Poes birth certificate, his fathers marriage contract, and a sworn statement of Gomez alleging a bigamous marriage.
Manapat went on official leave of absence a day after he was denounced at a Senate hearing for allegedly ordering
Tarin, Talabis and Llamera to come up with fabricated birth and marriage certificates of Poes father.
Manapat has maintained innocence of the charges and lamented that he was not given the opportunity to defend himself before the Senate investigation into the alleged fabricated documents.
Manapat said he went on leave of absence so he would not be accused of using his position when he filed perjury charges against Tarin, Talabis and Llamera before the Pasay City Prosecutors Office.
The Commission on Elections has thrown out the disqualification complaint filed by lawyer Victorino Fornier against Poe for lack of merit.
It is now pending on appeal before the Supreme Court. Delon Porcalla