Suspicious mortgage fraud activity that occurred at least four years ago induced filings in the third quarter to spike 20% from a year earlier.

Financial institutions filed 19,934 suspicious activity reports involving mortgage loan fraud  in the three months ended Sept. 30, up from 16,567 in the same period of 2010, according to the Financial Crimes Enforcement Network.

Nearly 62% of the filings in the quarter involved suspicious activity that began at least four years ago. In the year-earlier third quarter, that figure was 24%. Instances of alleged fraud stem largely from mortgage repurchase demands and filings from depository institutions related to originations during the height of the housing boom.

Reports of suspicious activity also involved loan workout or debt elimination; questionable refinance or loan modification attempts by borrowers or others targeting distressed homeowners; and Social Security number discrepancies submitted in the original loan application and the workout request.

The enforcement network found that 5,728 reports filed in the third quarter, 29% of the total, included activity that occurred between October 2009 and September 2011.

In January, President Barack Obama announced the formation of a mortgage fraud task force headed by New York Attorney General Eric Schneiderman. In the March issue of HousingWire magazine, Christopher Whalen discusses Schneiderman's role in investigating fraud and malfeasance in the financial markets, which he says should be understood separately from Washington agendas.

FinCEN said the top five states with fraud reports by per capita and in the third quarter were Hawaii, California, Nevada, Florida and Delaware.

The top five counties were Santa Clara County, Calif.; Honolulu; Orange County, Calif., San Bernardino County, Calif. and Palm Beach County, Fla.

"As housing markets look to recover, criminals persist in their efforts to prey on struggling homeowners, while financial institutions continue to uncover apparent fraud as they work through their portfolios of earlier mortgages now in default," FinCEN Director James Freis said. "FinCEN will continue to monitor these reports and work closely with law enforcement to help them track illicit actors."