The House Government Reform Committee -- which heard Baltimore Orioles first baseman Rafael Palmeiro's testimony in March that he had never used steroids, while he jabbed his index finger in the air for emphasis -- has opened an investigation into whether Palmeiro may have lied under oath.

Committee Chairman Rep. Thomas M. Davis III (R-Va.) spoke by telephone with Palmeiro -- suspended Monday for violating baseball's steroid policy -- on Tuesday night and informed him of the committee's plan to investigate the veracity of his March 17 testimony. During the conversation, Davis said, Palmeiro pledged to cooperate with the inquiry and repeated his assertion, first made during a conference call with reporters on Monday, that he did not know how the substance got into his system.

"He stayed with that story," Davis said in a telephone interview Wednesday. "I said, 'Raffy, you understand we have an obligation to pursue this, because you testified to us under oath,' and there is some question now as to how long [the steroid] had been in his system" at the time of the positive test.

"If there's anybody in the world I'd like to give a free pass to in this, it's Raffy," Davis said. "But I didn't give a free pass to [former president Bill] Clinton, and I can't here, either."

In a statement released by the team Wednesday, Palmeiro said: "I spoke with Congressman Davis yesterday and told him that I will fully cooperate with him and the Committee. I will provide them with any information they need and if he or any other Committee member has additional questions, I am ready and willing to answer each and every one of them."

Two New York newspapers reported Tuesday night that Palmeiro tested positive for stanozolol, a potent steroid, and a source with intimate knowledge of the matter confirmed it Wednesday morning.

"If it's true that he used that particular drug," said committee member Rep. Stephen F. Lynch (D-Mass.), "it's even more damning of Mr. Palmeiro's conduct in this case."

Palmeiro's agent, Arn Tellem, blamed Major League Baseball officials for Tuesday's leak of the name of the drug. "The confidentiality rules that the arbitrator set in this case have been broken by MLB," Tellem said in a statement. "Rafael has respected the rules by not discussing the specifics, but unfortunately MLB has not done the same. What MLB has done is outrageous and it undermines the integrity of their drug testing program. There is another side to this story, and Raffy will tell it soon. I hope that the public will wait to make a final judgment about Rafael until they hear his story in its entirety."

In reply, Rob Manfred, baseball's executive vice president of labor relations, said in a telephone interview, "Major League Baseball respected the confidentiality order that was imposed and the only one that has been talking about the facts of this case is Rafael Palmeiro."

Drug experts say it is difficult to imagine a scenario in which an athlete could inadvertently or unknowingly consume stanozolol, which is known as Winstrol or Winny. Stanozolol is the drug for which Canadian sprinter Ben Johnson tested positive at the 1988 Summer Olympics.

Stanozolol, which has a very distinctive structure, is not found in dietary supplements and has not been associated with supplement contamination, unlike steroids such as nandrolone.

Don Catlin, the director of the UCLA Olympic Analytical Laboratory in Los Angeles, said stanozolol showed up in 11.8 percent of positive drug tests recorded by the International Olympic Committee between 1988 and 2002. Only nandrolone and testosterone (as measured by a ratio test) showed up more often, Catlin said.

"If I was going to be drug-tested, I would use Winstrol before I would use something else," said a former bodybuilder who has used steroids and requested anonymity. "When you take it orally, in three weeks you are pretty much guaranteed that it will clear your system."

Davis said the committee will investigate what drug Palmeiro was found to have used, rather than accept the word of newspaper reports.

"We're nowhere near the 'p word,' " Davis said, referring to perjury charges. "But we have an obligation to look at this. If there are inconsistencies that we can't resolve, we may have to refer it" to the Justice Department, which handles federal perjury cases.

Davis said the committee already has some "third-party evidence" about how Palmeiro "could have gotten" the drug, and the circumstances under which he may have taken it. However, Davis would not elaborate about the nature of the evidence.

"He's going to have to give an explanation somewhere for how it got into his system," Davis said. "His public explanation is that he doesn't know how it happened."

While the evidence-gathering process has begun, a meeting of the full committee probably would not take place until after Congress's August recess -- although Davis has the option of calling a special session. Lynch estimated it would take two to three months, once the committee begins meeting, to reach a decision on whether the case should be referred to the Justice Department to pursue perjury charges.

Proving Palmeiro lied under oath -- if he did -- could be difficult. A baseball source with knowledge of the matter confirmed multiple newspaper reports that the positive test occurred in May, some two months after Palmeiro testified before Congress. However, it is possible for certain steroids to remain in someone's system for at least that long, experts say.

The committee could attempt to subpoena steroid testing results from previous seasons -- this is the first season in which baseball has revealed the names of players who test positive. However, his 10-day suspension -- standard for first-time offenders -- indicated he had not tested positive previously.

On Wednesday, following the newspaper reports that Palmeiro had used stanozolol, many in baseball questioned why Palmeiro had claimed two days earlier that his positive test was an accident -- or why his agents and lawyers had allowed him to claim that.

"They should be checking their malpractice policies," one baseball source said of Palmeiro's legal team.

During the flurry of phone calls and face-to-face conversations that took place Monday in the hours prior to the public announcement, at least one official advised Palmeiro to take one of two firm public stances: Admit everything and apologize, or say absolutely nothing.

Instead, Palmeiro, with his agent, Tellem, at his side during a conference call with reporters Monday afternoon, took the middle route, claiming his positive test was "an accident" but declining to answer specific questions about the nature of the positive test, citing a confidentiality agreement.

League and union officials have touted the Palmeiro case as proof that their system works, and Davis, who led the committee's blistering criticism of baseball's steroid policy during the March hearings, praised the league's handling of the Palmeiro matter.

"Baseball acted by the book," Davis said. "I don't think there is any stain on Major League Baseball. If anything, it shows they have a testing regime, and they enforced it."

However, Rep. John E. Sweeney (R-N.Y.) said the Palmeiro case merely highlighted the flaws in a system that has not been adequately fixed. Baseball's drug testing policy, he said, should not be administered by baseball itself. He said the program required more legitimate oversight, transparency and stiffer penalties.

"This just points out that what you really need is an independent objective entity doing the testing," Sweeney said. "In order for people to have confidence it really needs to be done by some outside entity.

"What if what Mr. Palmeiro seems to insinuate is true, and it really is truly an accidental occurrence? Why give any benefit of the doubt to that person if this system is so cloaked in secrecy?"

Staff writer Amy Shipley contributed to this report from Miami.

Rafael Palmeiro