New York ? A Secret Service ink expert who testified for the government at the Martha Stewart trial was charged Friday with lying repeatedly on the stand — a development that could cast a cloud of doubt over Stewart’s conviction.

Larry F. Stewart, 46, was charged by federal authorities with two counts of perjury and was suspended as Secret Service laboratory director.

Lawyers for Martha Stewart and her co-defendant and stockbroker, Peter Bacanovic, immediately claimed the arrest “undermines the integrity” of their convictions. Bacanovic’s lawyer said he would ask for a new trial.

Federal prosecutors insisted the perjury case does not compromise the guilty verdicts in any way.

At a brief court appearance Friday, Larry Stewart was released on $50,000 bail and a preliminary hearing was set for June 10. He did not enter a plea.