The BI did not identify the lawyers but executive director Roy Almoro said the six are all hearing officers who recommended to the Department of Justice (DOJ) the players recognition as Filipinos.
Almoro, however, stressed that the lawyers were apparently acting on the guarantee of civil registars that the papers were authentic.
"The papers were authentic but their contents were not," Almoro told The Star.
The PBA allows only Filipinos and foreigners with Filipino blood to play on a regular basis.
The upcoming probe is part of the BI bid to fast-track deportation proceedings against Asi Taulava, Davonn Harp, Rudy Hatfield, Andy Seigle, and Jonathan Ordonio, whose papers are in question.
The BI is also seeking opinion from the DOJ on the case involving Dorian Pena, Mick Pennisi and Alex Crisano, who were later added to the list of Fil-foreign players found by the two Senate committees to have submitted fake documents.
The BI has requested the DOJ for its opinion whether it can deport the eight despite already being recognized as Filipinos. Almoro said that if DOJ revokes the recognition it could immediately proceed with the deportation proceedings.
The lawyers of the players, however, are arguing that the recognition can only be revoked through court order.
Domingo also appointed Almoro as head of a four-man panel to conduct an administrative investigation.