Lawmakers offered many words of advice to FBI Director Robert Mueller on Friday as he described how the FBI plans to better organize itself to fight terrorism.

"In our quest to create a better, faster, more agile FBI, we have to be careful not to trample on the rights granted to every American under the Constitution," said Rep. Frank Wolf, R-Va., chairman of the House subcommittee reviewing the agency's annual budget.

"I'm concerned that in the rush to catch the bad guys, we will hurt the good guys," said Rep. Jose Serrano of New York, the panel's top Democrat.

Mueller was on Capitol Hill to discuss the FBI's new focus on counterterrorism. He said the agency is drawing hundreds of field agents from drug and other criminal investigations, and is training and inspecting agents to prevent them from committing civil liberties violations against law-abiding citizens.

"Agents understand the consequences of going beyond the Constitution," Mueller told the House Appropriations subcommittee that oversees the Justice Department and FBI.

Immediately after Sept. 11, the FBI assigned more than 6,000 agents to counterterrorism — six times the number before the attacks.

"That has leveled off to 2,000 now," Mueller said.

The FBI and CIA will also work together more effectively on intelligence matters, Mueller promised representatives, though all the information the agencies receive will also be subject to scrutiny by a new department of homeland security currently in the process of being created, say officials.

In a Senate hearing Thursday to discuss the administration's proposal to create a 170,000-person Cabinet-level department that draws on 22 agencies, Homeland Security Director Tom Ridge said that the staff will work to "connect the dots" even if it receives only scrubbed reports and analyses from FBI and CIA agents.

The new analysis will be aided by a fresh perspective outside the long-operating intelligence agencies, Ridge said.

"This would be the only venue where all the information gathered by all the intelligence agencies of the United States could be reviewed," Ridge said. "That integration has never occurred anywhere in the federal government before."

Lawmakers, however, expressed concern about turf wars, and the ability to analyze data and prevent future terror attacks.

"How is this agency to know what it doesn't know?" Sen. Mark Dayton, D-Minn., asked at a hearing Thursday of the Senate Governmental Affairs Committee. "You're adding another player to this equation."

The Associated Press contributed to this report.