Congressional Inquiry: How Did Shahzad Become U.S. Citizen?

CBS News has learned that Senator Charles Grassley (R-IA) is launching an inquiry into how Faisal Shahzad became a naturalized U.S. citizen in 2009 despite multiple law enforcement investigations into his background over the last 10 years.

Grassley sent Department of Homeland Security Secretary Janet Napolitano a letter today asking for the "Alien" file for Shahzad and his family members and for everyone who has been a reference or a sponsor for the terror suspect.

An Alien or "A" file includes visa and travel history, financial and personal information as well as any derogatory information from law enforcement. Grassley wants to know if this file was in the hands of the official who approved Shahzad's citizenship.

Grassley also wants Shahzad's arrival forms that he filled out each time he re-entered the United States and whether or not he sponsored other individuals to become citizens.

CBS news reported Wednesday that Faisal Shahzad had appeared on a Department of Homeland Security watchlist between 1999 and 2008 because he brought $80,000 of cash into the United States.

The New York Times reported on May 4, 2010 that the man who bought a condo from Shahzad, six years ago in May 2004 was visited at that time by investigators from the Joint Terrorism Task Force who asked questions about Shahzad.

Grassley wants to know how Shahzad became a US citizen if there was so much scrutiny into his background over the last decade. Grassley wants the documents by May 11, 2010.