WASHINGTON (CNN) -- A criminal investigation should be opened into whether the operators of Utah's Crandall Canyon mine purposely misled safety officials about mine conditions before the deadly 2007 collapse, the chairman of a House investigation committee said Thursday.
An Emery County sheriff walks past six yellow ribbons of hope at the Crandall Canyon mine in August.
Rep. George Miller, leader of the House Education and Labor Committee, released a report on the panel's investigation and said he has asked the Justice Department to look into whether the mine's manager and others had given all the facts to the federal Mine Safety and Health Administration about a previous incident at the coal mine.
He also criticized the agency for approving a risky work plan at the mine before the August disaster that left nine dead.
"The findings of this investigation demonstrate that the Crandall Mine tragedy might have been avoided at several key moments," said Miller, D-California. "They suggest that the mine owner did not act in the interest or safety of its employees, and that the Mine Safety and Health Administration failed these miners and their families."
Miller said mine executives, who invoked the Fifth Amendment to refuse interviews with committee staff, may have "deliberately and significantly downplayed" the extent of a previous cave-in when seeking MSHA's approval for their plans.
"It's a question of whether they made false statements and whether or not they engaged in a conspiracy to promote those false statements and the fact that everybody involved in that process has taken the Fifth gives us cause for concern," he said.
A lawyer for Crandall Canyon manager Laine Adair called Miller's request for a criminal inquiry "deeply disappointing and utterly unjustified." And Genwal Resources, the subsidiary of mine owner Murray Energy that oversaw the mine, accused Miller of trying to "concoct" a criminal case out of a disaster that killed six miners and three would-be rescuers.
"Laine Adair is an honest and plain-speaking man whose integrity and professionalism are well-established in the Utah mining community where he has worked for over 30 years," company attorney Kevin Anderson said in a written statement. "Genwal Resources stands behind Mr. Adair, and we believe Mr. Miller's efforts to impugn Mr. Adair and other individuals through today's announcement is deplorable."
Allyn Davis, the MSHA district supervisor at the time, told investigators that the description of a March 2007 cave-in did not match the description he received from Adair, Thursday's report states. It concluded Adair and others in the company "may have purposely misled MSHA" about the earlier incident, fearing that regulators would close the mine.
The report also says mine officials continued to mischaracterize the incident after the fatal collapse "in an effort to downplay the foreseeability of the August incident."
But Gregory Poe, Adair's attorney, criticized Miller's request for a criminal investigation.
"Mr. Adair has earned an impeccable reputation through decades of service in the Utah mining industry," Poe said in a written statement. "The facts will show that Mr. Adair's conduct was entirely proper. We are confident that the Justice Department will agree that a prosecution is wholly unwarranted."
A Labor Department report criticized MSHA officials this year for approving plans for the risky mining technique, known as "retreat mining," that was in use before the collapse. In the process, miners remove pillars of coal that support the roof of a chamber one by one, allowing the roof to collapse behind them.
Mine owner Bob Murray repeatedly denied that his company practiced retreat mining at Crandall Canyon in the days after the disaster. He later admitted that the practice had been used at the mine but said it was not being done at the time of the disaster.
On Thursday, Genwal accused Miller of leveling "unfounded conclusions" and "reckless allegations."
"As with many of his prior statements, there is no credible basis for Mr. Miller's reckless allegations. They are merely political grandstanding as he continues to play to his constituents," Anderson said. "We are confident that any impartial investigator will reject Mr. Miller's allegations."
In a statement Thursday, MSHA urged everyone not to jump to conclusions.
"The official MSHA accident investigation, conducted by the recognized experts on mine safety and health, will determine the root causes of the accident at the Crandall Canyon mine last year," the agency said. "Until this report is released, it would be premature and speculative to comment on Congressman Miller's review."
The ranking Republican on Miller's committee, Rep. Howard "Buck" McKeon, questioned Miller's efforts to investigate the disaster "before official investigations are complete."
"Today's report unfortunately offers little in the way of new information to the families of those who lost their lives at Crandall Canyon," said McKeon, also of California. "It is clearer now than ever that we will not have a complete picture of what went wrong at Crandall Canyon until the Mine Safety and Health Administration completes its investigation and issues its findings."
The results of MSHA's investigation are expected in June, spokesman Matthew Faraci said.
CNN's Edvige Jean-Frangois contributed to this report.