Prosecutors have asked a judge to disqualify the lawyer representing former Massachusetts House Speaker Salvatore DiMasi in his federal corruption case, because the lawyer also gave advice to a prosecution witness.

Court documents unsealed this week show that Steven Topazio, DiMasi's former law associate, testified that he consulted DiMasi's lawyer, Thomas Kiley, as soon as questions surfaced about Topazio's relationship with the software company whose multimillion dollar state contracts are at the center of the case against the former speaker.

Prosecutors say Topazio was the conduit for monthly $4,000 payments from the company to DiMasi. Topazio is now a government witness.

The Boston Globe reports that prosecutors argue that Kiley has a conflict of interest by representing "two adversely positioned clients."