Zwerner has filed his answer, here, which states his side of the story, albeit in summary fashion.
Some key points from the answer:
1. At the key time of his reputed voluntary disclosure in 2008, Zwerner was represented by "a tax attorney, Dennis Kleinfeld, of the then reputable law firm Rothstein Rosenfeldt & Adler, P.A. (“RRA”)." Notice the words "then reputable." See Wikipedia entry on Scott W. Rothstein here, and paragraph 5 of the compliant quoted below. Mr. Kleinfield's current law firm bio is here. I understand that Mr. Kleinfeld referred Zwerner to Mark Nurik who represented Zwerner before the IRS.
2. Here is a key allegation in the answer (pp. 3 and 4):
4. On February 10, 2009, the RRA lawyers met with IRS Criminal Investigation Division (“CID”) to go over the voluntary disclosure. On February 17, 2009, IRS CID issued a letter stating that no criminal action would take place, but the identity of the client had not been disclosed at the February 10, 2009 meeting. Nurik then advised Zwerner that his voluntary disclosure had occurred and he should file the amended returns for tax years 2004 – 2006. As instructed by his lawyers in March 2009, Zwerner immediately filed the amended tax returns and the FBARs for 2004, 2005, and 2006, and paid the tax and interest owing.As narrated, Zwerner's prior tax counsel did not complete the voluntary disclosure by identifying Zwerner to CI and making a full disclousure. Instead, he told Zwerner to do a quiet disclosure by filing amended returns. The implication and allegation is that Zwerner had no reason to question whether his tax counsel was giving good advice and that Zwerner reasonably believed and took affirmative objective steps to implement a voluntary disclosure.