. >> i am officer nicky johnson from international revenue service, do return the call before we take any action against you. >> melissa dagan a mother from salt lake city lost nearly $16,000, money she was saving to buy a home. >> i'm sick to my stomach embarrassed a lose that all this money -- >> the scammers are often from overseas and manipulate caller i.d. to appear they were the irs. they sometimes know personal information, insist you owe back taxes and demand money with a prepaid cash card or wire transfer. even one of the treasury department's top officers got a call demanding he paid up. >> supposedly $750. >> or they are going to arrest you? >> correct. >> targeted across every state with more than $15 million stolen. each victim has lost on average $5,000. >> the fraudsters have clearly upped their game and we must do the same. >> this week congress held hearings how to stop it. >> when the money dries up the criminals will go away. >> the irs always sends a letter through mail first and never call. catching these fraudsters will be extremely difficult and may not be able

. >> i am officer nicki johnson from internal revenue service. and do return the call before we take any action against you. >> reporter: telling unsuspecting victims they owe back taxes. targeting more than 360,000 people in every state. stealing a total of $15.5 million. 32-year-old salt lake city mom of three melissa dagan lost almost $16,000. money she was saving to buy a home. >> i'm just sick to my stomach, embarrassed, you know, just -- a loss of all this money. >> reporter: even those who aren't scammed could lose money. the irs announcing more than $1 billion in refunds from 2011 alone hasn't been claimed from an estimated 1 million taxpayers. and the deadline to get it is next month. now, the irs, if it's the real irs, will contact you first by mail, not by phone or with a robo call, and david, they will never demand immediate payment over the phone. >> good tips, as always. mara, thank you. >>> when we come back here tonight, the american astronaut back on solid ground this evening. you'll see it. >>> also, the fireball in the skies ov