According to a source familiar with the chronology, Palmeiro tested positive for a steroid in May and appealed the ruling in secret arbitration proceedings in June.
During that time, Palmeiro's situation was known only to certain representatives from Major League Baseball and the players union until it was made public Monday, the source said.
Newsday reported in today's editions that a source familiar with Palmeiro's drug test said the results showed positive results for stanozolol, which experts on steroids say is a "very tough steroid" that almost assuredly did not enter Palmeiro by way of accident or sabotage.
"If it's stanozolol, this was a deliberate act," said Gary Wadler, a Long Island doctor who is one of the world's foremost authorities on steroids. "The likelihood of sabotage is remote and improbable, and to suggest as much would be to send people on a wild goose chase."
Through a spokesman, Palmeiro's agent, Arn Tellem, citing an order of confidentiality, declined to comment about the test result.
Stanozolol has a long history in sports. Canadian sprinter Ben Johnson was stripped of his 100-meter gold medal in 1988 after testing positive for the drug.
The previously undisclosed chronology of Palmeiro's case has attracted the attention of Congress, largely because the first baseman emphatically told the House Government Reform Committee in March that he had never used steroids.
According to aides, the committee wants specific information from baseball about Palmeiro's case, including details of when his drug test was conducted, analyzed and disclosed to the player and the team.
Some committee members and staff members also want baseball to reveal what banned substance triggered the positive test.
The committee was drafting a tentative information request to baseball yesterday.
"Rafael was able to connect with Chairman Davis late this afternoon and assured him he will cooperate fully and provide his committee with any information it requests," Tellem, Palmeiro's agent, said yesterday, referring to Rep. Tom Davis, a Virginia Republican who is chairman of the committee.
The failed test was kept confidential during the lengthy appeal, and the source said some close to the situation, including the Orioles organization, did not learn of Palmeiro's positive drug test until Friday.
Arbitrator Shyam Das told the parties involved that he had denied Palmeiro's appeal, but he did not sign off on it until Monday, when it was released by Major League Baseball. That, not last weekend's Hall of Fame induction, delayed the suspension, the source said.
Palmeiro played in all three weekend games and did not appear distracted. He had four hits, including his 18th homer of the season, in 11 at-bats. He batted .299 with six homers and 19 RBIs last month.
As part of baseball's new drug policy, players are randomly tested and the urine is divided into two samples, A and B.
The lab first tests part of the A sample. If it comes up positive for steroids, the rest of that sample is tested. If that is also positive, Major League Baseball, the players union and the player are informed.
The player has the option of asking that sample B be tested. Also, the player can challenge the test with baseball's four-person Health Policy Advisory Committee, made up of a union representative, a baseball representative and two doctors.
If any one of the four decides that the challenge has merit, it is forwarded to a three-person arbitration panel consisting of a baseball lawyer, a union lawyer and an independent arbitrator.
Palmeiro challenged his drug test and won the right to plead his case before the panel. He wasn't the only one of the first seven suspended players to make such a challenge but was the first to receive a hearing.
Since then, Seattle Mariners pitcher Ryan Franklin also has received a hearing. It was announced yesterday that Franklin was also suspended for 10 days, becoming the eighth player found to have violated baseball's drug policy.
At the arbitrator's hearing, the player can address the panel, which Palmeiro did in June.
Because of the way the three-person arbitration panel is constructed, only the independent arbitrator makes a ruling.
It can take many weeks for the arbiter to review a case, which is why Palmeiro's suspension was not announced for months after the original test.
Das refused to comment on the case.
Members of Congress and their staffs said yesterday that they intend to request more information about the case from Major League Baseball.
"There's a lot people don't know," said Robert White, a spokesman for Davis. "I think what we're doing now is just gathering facts about the matter."
The committee is considering sending baseball officials a letter or seeking the information in another way.
White said it is too early to comment further. Another aide familiar with the committee's thinking said the panel wants a detailed chronology.
There have been contacts between members of Congress and baseball since Monday's announcement of Palmeiro's suspension, but the committee does not have all the information it wants.
Palmeiro testified before the committee March 17, along with Orioles teammate Sammy Sosa and a handful of other current and former players and baseball executives. Palmeiro pointedly denied using steroids and offered to be an advocate in educating young people about the risks of steroids.
Palmeiro was summoned to testify largely because of a misunderstanding. Committee staff members, looking for cooperative witnesses, had read a Florida newspaper article suggesting that Palmeiro would be happy to appear. It turned out he was anything but. Palmeiro was then subpoenaed.
Since Monday's suspension announcement, several House members have said they want to know whether Palmeiro lied to Congress.
Palmeiro has said that he didn't intentionally used a banned substance and that he told the truth under oath.
Palmeiro's case might give a push to legislation that would place Major League Baseball, the National Football League, the National Basketball Association and the National Hockey League under the disciplinary regime faced by Olympians who use performance-boosting drugs: a two-year suspension for a first violation and a lifetime ban for a second.