Investigators found no wrongdoing by a Department of Homeland Security (search) agency that helped Texas police track down the private plane of a state legislator who fled with other Democrats to Oklahoma in a political dispute.

The department's inspector general concluded in a report released Monday that a dispatcher at the California-based Air and Marine Interdiction Coordination Center (search) made eight phone calls that took no more than 40 minutes to track down a Piper Cheyenne belonging to state Rep. Pete Laney, a Democrat.

Laney flew to Ardmore, Okla., last month to prevent a vote on a congressional redistricting bill in the Texas House that had been pushed by U.S. Majority Leader Tom DeLay. Fifty other Democrats also fled to Ardmore.

The investigators said that help given to the Texas Department of Public Safety (search) had "no reducible effect" on the center's mission.

"This is a nominal use of [Department of Homeland Security] resources," the investigators said.

The center, part of the Bureau of Immigration and Customs Enforcement (search) in the Homeland Security Department, monitors drug traffickers and possible terrorist activities.

Democrats have been urging Homeland Security Secretary Tom Ridge to release transcripts of the conversations between the center and the department. They have alleged that DeLay or other Republicans used the agency for political purposes. DeLay has said he did not contact the agency.

"What do the Democrats say now about their lies?" said DeLay spokesman Jonathan Grella.

In Austin, Bob Richter, a spokesman for House Speaker Tom Craddick, said the findings were "what we expected all along."

The investigators' findings are "yet another authority, concluding that there were no inappropriate actions taken" in the attempt to round up the Democrats, said Kathy Walt, spokeswoman for Gov. Rick Perry.

Center staffers say the Texas DPS called on May 12 requesting for help in finding an aircraft "believed to be overdue." The center told investigators they average 30 to 40 calls a day requesting assistance from individuals, localities and states.

"We had a plane that was supposedly to be going from Ardmore, Okla., to Georgetown, Texas. It had state representatives in it and we cannot find this plane," the DPS told the center, according to the redacted transcript.

The agency said it blacked out names of employees and other information for privacy reasons, but Lt. Will Crais of DPS is identified as a caller to the center in a transcript released by the department.

The center's operations manual says it will help federal, state and local law enforcement agencies for humanitarian efforts if it has the resources, the report said.

After the center was unable to find the Texan's plane, it suggested DPS call the Dallas-Fort Worth airport to request a search and rescue. Crais initially turned that down. But he later called back to get information on how to start one, telling the center that he talked with a state representative and "they want to do a search and rescue."

Crais has said in a deposition that he acted alone in contacting the center. But the investigator's report says several individuals requested someone or something -- that information also was blanked out -- look for the airplane.

Revelations that the anti-terrorism agency had assisted in the search prompted a string of letters from lawmakers in Congress, including presidential hopeful Sen. Joe Lieberman, D-Conn., who chairs the House Government Affairs Committee, and Rep. Jim Turner of Texas, ranking Democrat on the House Select Committee on Homeland Security.

Lawmakers also questioned whether the agency has enough safeguards in place to prevent misuse of anti-terrorism resources. The investigation did not address whether the caller acted improperly by leading the center to believe the plane was in trouble.

Democrats have insisted that the department let them inspect all transcripts, recordings and related documents. But Ridge has declined, saying the probe was a "potentially criminal investigation."

Some Democrats have invoked a rule that allows seven members of the House Government Reform Committee to compel Ridge to release the documents and tapes. Ridge has until Thursday to comply.

Rep. Lloyd Doggett, D-Texas, was unsatisfied with the heavily redacted report.

"This attempt to filter the truth raises as many unanswered questions as it offers gaps and omissions. It's really more of a 'Don't Ask, Don't Tell' policy than a comprehensive investigation," Doggett said in a statement.