But lead attorney Joel Brodsky says Peterson's trial will begin in June as scheduled.
Attorney Andrew Abood says the motion he and attorney George Lenard filed Wednesday cites "irreconcilable differences." Neither he nor Brodsky would elaborate.
Brodsky says attorney Joseph Lopez will join the defense team. Lopez represented one of several reputed mobsters convicted in 2007 in a major racketeering conspiracy.
Peterson is charged with murder in the 2004 death of Kathleen Savio. He's a suspect in the disappearance of his fourth wife, Stacy Peterson but hasn't been charged.
Peterson denies any wrongdoing.