Federal investigators searched Arizona Diamondbacks reliever Jason Grimsley's house Tuesday as part of their investigation of steroid use in baseball.

Thirteen agents searched Grimsley's house in Scottsdale, Ariz., for six hours, 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 BALCO steroid scandal here 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.

Diamondbacks managing general partner Ken Kendrick said in a statement the team learned of "this situation late this afternoon," but declined further comment.

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. Authorities said when he 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," Novitsky wrote.

After the BALCO investigation, Major League Baseball toughened its testing program for performance enhancing drugs and included testing for amphetamines for the first time this season.

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 Bay Area Laboratory Co-Operative with the performance-enhancing drug known as "the clear."

A federal grand jury in San Francisco is also investigating whether San Francisco Giants slugger 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 Illinois-based nutritional supplement scientist Patrick Arnold, BALCO president Victor Conte, Bonds' personal trainer Greg Anderson, BALCO vice president James Valente and track coach Remi Korchemny.