MANILA - Sen. Teofisto "TG" Guingona III on Thursday said he has signed a letter urging Senate President Franklin Drilon to reconsider his decision not to sign a subpoena for businesswoman Janet Lim Napoles, the alleged mastermind in the P10 billion pork barrel scam. In his opening statement before the Senate Blue Ribbon Committee, Guingona said it was the third time that Napoles has failed to appear before the Senate. Napoles was previously summoned to the Senate in 2006 in connection with the P728 million fertilizer fund scam but failed to testify after Malacañang barred government officials and other resource persons from attending the probe. He said Napoles again ignored a Senate summons in 2008. Guingona said he has issued a letter addressed to Drilon "urging him to reconsider his position or his decision not to approve the subopoena issued to Janet Lim Napoles." Drilon earlier said he will not sign the subpoena for Napoles to attend the Senate Blue Ribbon Committee inquiry on the PDAF scam in deference to the Ombudsman's own recommendation. At least 38 individuals including Napoles have been charged with plunder, graft and malversation of priority development assistance funds before the Ombudsman.