Joel Brodsky, one of Peterson's lawyers, said Steve Greenberg was having sex with a cable news reporter during the trial to help generate more publicity and that he suffers from a mental illness called "pathological narcissism."
Brodsky offered no evidence to back up either allegation, the Chicago Sun-Times said Tuesday.
The charges come in response to a Greenberg court filing seeking to overturn Peterson's conviction on grounds of incompetent representation. Greenberg said Brodsky committed a "smorgasbord of ethical violations."
Brodsky is seeking to distance himself from representing the former suburban Chicago cop in a civil suit filed by the family of Peterson's third wife, Kathleen Savio. A jury convicted Peterson of killing earlier her this year.