UPDATE 1-FBI mortgage fraud probes grow to 2,600 cases

* Mortgage fraud schemes evolving

* Most involve losses of more than $1 million (Adds comments, details, background)

WASHINGTON, Sept 16 (Reuters) - The Federal Bureau of Investigation's caseload for mortgage fraud has continued to grow as homeowners cope with the shattered housing market, FBI Director Robert Mueller told the U.S. Congress on Wednesday.

"The schemes have evolved with the changing economy, targeting vulnerable individuals, victimizing them even as they are about to lose their homes," he said in prepared remarks to the Senate Judiciary Committee.

He told the panel that the FBI has more than 2,600 cases open with most of them involving losses of over $1 million. That is more than triple the number three years ago and up from 2,400 cases Mueller said were open in May.

The FBI has shifted its investigative resources to focus on mortgage fraud and assigned about 300 special agents to the task, Mueller said, adding that their focus has centered on what he described as "industry insiders."

Economists have cited the housing bust that left banks holding souring mortgage securities as the primary cause of the deep recession that has swamped the U.S. economy since December 2007.

Federal Reserve Chairman Ben Bernanke said on Tuesday he believed the worst of the recession was over.

Like the mortgage fraud caseload, the FBI's corporate fraud investigations have grown as well, according to Mueller, rising to 580 open cases, up from 560 in May. The FBI has declined to identify any companies under criminal investigation.

"We are on pace to significantly increase our production over last year," Mueller said in the written testimony.

In other comments, Mueller said the FBI also has 2,400 pending healthcare fraud investigations, but gave no further details. (Reporting by Jeremy Pelofsky, editing by Eric Beech)