I did find FBI documents that strongly suggest Chuckie English was also an informant. I don't think he cooperated on the same high level as Pierce or Blasi, but I do think he shared some confidential information with Roemer(and the FBI) about the time Giancana fell out of power in the late 1960s.

BTW, if Blasi did kill Giancana, I wonder if Roemer knowingly protected his source from prosecution. Roemer was adamant that Blasi had nothing to do with the murder but never said exactly why. Did he just take Blasi's word for it? Did he have evidence Blasi didn't do it? Or was he protecting a killer/source?