The high cost of reviewing foreclosures at big banks has ignited an inquiry by one member of Congress.

Carolyn Maloney, a New York Democrat who is a member of the House Financial Services Committee, has asked the federal regulators who oversee foreclosure reviews to provide details about the independent contractors who examined borrowers’ cases. The contractors reportedly received more than $1 billion in fees, which ultimately led to a $3.3 billion cash settlement for borrowers.

Regulators required the foreclosure reviews in 2011 after evidence emerged of rampant improprieties by the banks that serviced troubled loans.

The audits were supposed to cover some four million loans that entered foreclosure during 2009 and 2010.