Thirteen agents searched Grimsley's house in Scottsdale, Ariz., for six hours Tuesday, according to Internal Revenue Service agent Mark Lessler, who would not say what they found.
In seeking a judge's permission for the search, investigators who cracked the Bay Area Laboratory Co-Operative steroid scandal said Grimsley initially cooperated in the probe. He withdrew his assistance in April, but not before he allegedly made "extensive statements" about illegal drug use, "for the purpose of performance enhancement," according to the court documents.
IRS agent Jeff Novitsky told the federal judge that investigators wanted to search the right-hander's house for "any and all records showing contact or relationship with any and all amateur or professional athletes, athletic coaches or athletic trainers" regarding illicit drug use and purchases.
According to Novitsky, Grimsley told him the names of other players he believed were using, but the names of those players were blacked out of the court records.
"I have no comment about that and no idea about that," Grimsley told The Arizona Republic on Tuesday, hours before the Diamondbacks played the Philadelphia Phillies.
After Arizona's 10-1 loss, manager Bob Melvin said news of the investigation might have affected the team. Grimsley spent the game in the bullpen and warmed up at one point.
"Certainly, it locks you up for a little bit, but down the road we'll be fine," Melvin said.
"We haven't convicted this guy. This is an ongoing investigation. I just think that the effect on us today, as we heard about one of our teammates, it certainly had an effect on us. Nothing's been proven. He hasn't been proven guilty of anything. It's just, there's allegations."
Diamondbacks managing general partner Ken Kendrick issued a statement saying, "We were first informed of this situation late this afternoon. This is a federal investigation, and as long as it is active and ongoing, we are prohibited from making any further comments."
Grimsley's locker was cleared out on Wednesday morning and the Diamondbacks have scheduled a 2:30 ET press conference. ESPN's Pedro Gomez reports that Grimsley has either been designated for assignment, meaning the team owns rights to his contract for another 10 days, or that he has been released outright. It's unclear at this point which action the team has taken. Grimsley is no longer on the Arizona roster.
Grimsley began his big league career with Philadelphia in 1989 and has pitched for Cleveland, California, the New York Yankees, Kansas City, Baltimore and Arizona. He has a career record of 42-58 with a 4.77 ERA.
According to court documents, Grimsley failed a league drug test in 2003. Grimsley claims in the affidavit that then-GM Allard Baird told him of the flunked test.
"That simply isn't true," Baird told ESPN. "The tests were anonymous, and none of us knew who tested positive. We had no information on the tests."
Authorities said when Grimsley was cooperating, he admitted to using human growth hormone, amphetamines and steroids.
He added that amphetamine use was prevalent in pro baseball, and that it was placed in coffee in clubhouses -- marked "leaded" or "unleaded" to indicate which pots contained the drugs -- Novitsky wrote.
The Republic reported that Latino players were cited by Grimsley in the court documents as a major source of amphetamines, as were major leaguers on California teams who could easily travel to Mexico to buy the drugs.
The newspaper reported that the affidavit, which was filed in U.S. District Court in Phoenix, said that Grimsley took delivery of two kits containing human growth hormone at his home on April 19.
Word of the Grimsley investigation comes nearly two months after an Illinois-based scientist prominent in the field of sports nutritional supplements pleaded guilty to supplying the BALCO lab with the performance-enhancing drug known as "the clear."
Patrick Arnold pleaded guilty to one count of conspiracy to distribute steroids to BALCO, a steroid ring that San Francisco investigators broke up two years ago. Those same authorities are targeting Grimsley.
Arnold is scheduled to be sentenced in August and most likely will face three months in jail and three months of home detention.
A federal grand jury in San Francisco is also investigating whether San Francisco Giants outfielder Barry Bonds lied under oath about using "the clear." A separate federal grand jury is probing who leaked Bonds' testimony from the BALCO investigation to the San Francisco Chronicle.
So far, the BALCO probe has netted guilty pleas from Arnold, BALCO president Victor Conte, Bonds' trainer Greg Anderson, BALCO vice president James Valente and track coach Remi Korchemny.
Information from The Associated Press was used in this report.