I received the same type of message...and needless to say it was scary. This must be some new form of tactic to get people to call. Before I called, I googled the number...I knew something made no sense. If there was anything that was "serious" a letter from the IRS or somewhere else would be mailed to you...this is what I was always taught in order to avoid scams.
I got this call on a Saturday. It felt like a scam, but it's a good scare tactic- "there's a legal notice pressed against your name", "it's urgent that you return this call"- and I almost called back. Thank goodness for google and sites like this! Thanks for posting, everyone. I will not be returning Mr. Sean Marshall's call.
Called my grandmother's house on 12/22 saying they have affidavit from the Crime Investigation Dept of the IRS. Do not call them back or just hang up. It's a scam. I found this article on the IRS website: http://www.irs.gov/uac/Newsroom/IRS-Reiterate ... -Telephone-Scam and you can report it here: http://www.treasury.gov/tigta/contact_report_scam.shtml