NEW : Federal judge tells attorneys to expect ex-mistress to testify for government . Edwards is the ex-mistress of 30 years Democratic presidential candidate Edwards . John Edwards ' upcoming criminal trial will look at whether campaign money went to her . Edwards denies any wrongdoing .
NEW : Federal judge tells attorneys to expect ex-mistress to testify for government . Rielle Hunter is the ex-mistress of 2008 Democratic presidential candidate John Edwards . Edwards ' upcoming criminal trial will look at whether campaign money went to her . Edwards denies any wrongdoing .