Phone scam, don't answer. Claiming to be chief investigator for the IRS.

There is a fairly common IRS or "tax scam" being practiced by scammers in both Canada and the USA.
USA tax payers should read this:
http://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
Note particularly the links at that site, warning of the scam!

Received a phone message called by this number, claimed to be "John Smith" from IRS Criminal Investigation Division and an arrest warrent has been put on me and personal property is being monitored.  Gave a call back number 202-241-4529...  It's a scam!  Called IRS Customer service and got confirmation that it is a scam!  Reported this scam to Treasury Investigator General for Tax Administration.

IRS obviously has not done anything about these scampers because I just got a phone call from them as well.

Today 11/03/2014 this number called me, a women said she's an IRS agent. first she said " you will get arrested today if you don't pay 4000 cash  now " she was very firm and told me to get the cash  now from the bank otherwise a police officer will come to arrest me , she is very professional doing scams. I believe she is from India or Pakistan . Be careful it is a scam , do not  give money to anyone ! IRS will never ask for cash by phone.