A noted scientist in the sports nutritional supplement world pleaded guilty Friday to supplying the Bay Area Laboratory-Cooperative with the performance-enhancing drug known as "the clear."

Patrick Arnold pleaded guilty to one count of conspiracy to distribute steroids. He's scheduled to be sentenced in August and will likely face three months in jail and three months of home detention.

Arnold left the federal courthouse with commenting to reporters.

A federal grand jury indicted Arnold in November on conspiring with BALCO founder Victor Conte to distribute the once-undetectable substance tetrahydragestrinone. He initially faced three conspiracy counts, but two were dropped in exchange for his plea.

Arnold's plea comes as a grand jury is investigating whether Barry Bonds, the San Francisco Giants outfielder, lied about using "the clear" to another grand jury that investigated the BALCO lab more than two years ago.

So far, the BALCO probe has netted guilty pleas from Arnold, Conte, Bonds' trainer Greg Anderson, BALCO vice president James Valente and track coach Remi Korchemny.

Arnold, 39, was snared after federal agents raided his Champaign, Ill., lab last year.

Prosecutors say Arnold was intimately involved with distributing steroids through BALCO from 2000 to 2003, and at one point wired a large sum of money to China for the ingredients to make the drugs.

According to leaked excerpts of Bonds' testimony reported in the San Francisco Chronicle, Bonds told the BALCO grand jury he used a "clear" substance and a cream given to him by Anderson.

Bonds, who is approaching Babe Ruth's home run record, testified that Anderson informed him the substances were the nutritional supplement flaxseed oil and a rubbing balm for arthritis.

Arnold was known for introducing the steroid precursor androstenedione to the United States. Nicknamed "andro," the chemical came to public attention in 1998 when St. Louis Cardinals slugger Mark McGwire said he used it when he broke baseball's single-season home run record.

The indictment against Arnold alleged he trafficked in performance-enhancing drugs that were designed to avoid detection by sporting leagues, including the U.S. Anti-Doping Agency, Major League Baseball and the National Football League.

Bonds hit his 711th career home run in San Francisco's 9-7, 11-inning loss to New York on Wednesday, placing him three homers behind Babe Ruth for second on the career list, trailing Hank Aaron (755).