He's been called high-minded, a trailblazing lawman and "America's top steroid cop."

For someone who does his best work behind the scenes, federal agent Jeff Novitzky is hardly a stranger to the spotlight. And depending on the results of an ongoing investigation into the sometimes-shadowy world of pro cycling, he could soon become better-known still.

After hounding home-run king Barry Bonds for years and wringing a confession from Olympic sprinter Marion Jones, Novitzky is leading an investigation that has questioned sponsors and examined claims from former teammates of Lance Armstrong, the seven-time Tour de France champion. A grand jury has been seated in Los Angeles to hear evidence in the investigation over the coming weeks and months, and Armstrong sponsors Trek Bicycle Corp. and Nike each said Friday that they've been contacted by federal agents.

"I'm just glad he ain't after me," said attorney Richard Emery. "He is a nightmare for anyone that's he's focused on."

Emery represents Brian McNamee, the one-time personal trainer who accused former New York Yankees pitcher Roger Clemens of using steroids. The attorney ticks off a list of qualities that anyone who's worked with Novitzky would recognize and even his critics would concede: smart, meticulous, sophisticated, well-prepared and "straight as an arrow."

"He's creative," Emery added, "a bulldog. And very charming in his ability to bring people out."

But the people Novitzky pursues complain his tactics range much further afield.

Defense attorneys have accused him of carrying out vendettas against their clients, leaking information, fabricating evidence and intimidating witnesses along the way. More than one judge has raised doubts about the way he conducts investigations.

"What ever happened to the Fourth Amendment?" U.S. District Judge James Mahan wrote about a 2004 search-and-seizure case, in which Novitzky had a warrant to collect information on 10 baseball players -- but ended up seizing material from more than 100.

Like Mahan, two other district court judges ruled the government acted illegally. One said the government's tactics constituted "harassment." A specially convened 11-judge panel of the 9th U.S. Circuit of Appeals agreed; Novitzky was required to return the names and has been prohibited from using them to expand his investigation. A government appeal is pending.

That hasn't deterred prosecutors from taking a shot with Novitzky.

"Despite the criticism that has been lofted his way, he has always been able to prove his critics wrong," said Kevin Ryan, the U.S. attorney in San Francisco during the height of the BALCO prosecutions. "He's relentless. He's ethical. He's a very good investigator."

Novitzky has carved out a specialty going after high-profile sports figures by bringing an athlete's pedigree and an accounting degree to his work, first with the Internal Revenue Service, and, since spring 2008, with the Food and Drug Administration.

What quickly set him apart from the other government investigators scouring financial records was his willingness to crawl into a trash container behind the Bay Area Laboratory Co-Operative in 2002 and collect the documents himself. Next, he took a crash course in performance-enhancing drugs, or PEDs, from one of the best in the business.

"As a result of the BALCO investigation he became well-known in government circles," said Don Catlin, the respected Los Angeles chemist and longtime anti-doping crusader who tutored Novitzky. "He became a star."

Novitzky's name surfaced again this spring, when allegations of widespread doping by disgraced former tour winner Floyd Landis, a former Armstrong teammate, breathed new life into an existing federal probe looking into one of pro cycling's lower-rung teams.

Douglas Miller, assistant U.S. attorney for the Central District of California, has refused to comment on the composition, scope or targets of the investigation. But the issuing of subpoenas to cyclists and Armstrong sponsors has suggested that at its center is the former Tour champ, who became a global sporting brand and hero to cancer survivors as he dominated cycling from 1999-2005, all the while combating suspicions that he doped.

Armstrong has long insisted that he has never used performance-enhancing drugs, and he has test results to back him up. His attorneys have complained that cyclists are being offered deals on their own drug use if they come forward with admissions that implicate him. Armstrong himself has said he's happy to participate in a legitimate investigation but not a "witch hunt."

Novitzky, who frequently shows up in the courtroom for cases he works on, routinely declines interviews, saying publicity hampers his ability to do his job.

He told an AP reporter who recently showed up on his doorstep, "I ain't talking, man."

Novitzky stands an imposing 6-foot-6 and at age 43, still looks like the basketball and track standout he was at nearby Mills High School, before knee and back injuries derailed his collegiate athletic career. The son of a high school basketball coach, he still lives near his parents and had just returned from one of his daughters' volleyball practices.

With one daughter clinging to a leg, Novitzky repeated, "I ain't talking," and waved off any further questions.

Armstrong attorney Tim Herman complained in a letter to Miller last month about leaks pertaining to the investigation. He also questioned whether it was an appropriate use of federal resources, time and money "to ‘investigate' any sport, much less European cycling, especially when the principal source of the allegations (Landis) is a self-confessed perjurer."

The advocates for cleaning up sports think it is worth investigating.

To them, Novitzky is a hero. He does the dirty work pro sports leagues won't do themselves, whether that means testifying in a trial, twisting arms or leading a raid, as he did when agents shut down the Champaign, Ill., lab of Patrick Arnold, the chemist behind a BALCO steroid known as "the clear."

Arnold subsequently pleaded guilty to conspiracy to distribute steroids. The investigation resulted in a half-dozen other guilty pleas or convictions and reportedly cost $50 million. The longest sentence was handed to Troy Ellerman, an attorney for BALCO founder Victor Conte, and vice president James Valente, who leaked details of the case to the San Francisco newspaper reporters who wrote "Game of Shadows." Ellerman was given 2 1/2 years.

Novitzky and several other IRS agents in the BALCO case who accompanied him in a raid on the home of Bonds' personal trainer were investigated and cleared of any wrongdoing after $600 turned up missing following the seizure of $63,920 in cash from a safe and a drawer.

Novitzky also denied reports at the time that he was planning to write a book about the BALCO case. According to the IRS report that exonerated Novitzky on that matter as well, he told investigators any talk about a book deal "could have been a misconstrued comment that was made as a joke and overheard incorrectly by others."

Conte wound up pleading guilty to two of the 42 charges against him before trial and served four months in a minimum-security prison.

In a recent interview, Conte repeated an earlier claim "that yes, athletes cheat to win, but the government agents and prosecutors cheat to win, too." He also questioned whether the results in such cases justified the effort.

"In the economic climate we're in," Conte added, "knowing about corporate fraud, environmental fraud, health case fraud, my opinion is taxpayers are more concerned about putting a roof over their head, food in their mouth and having health care than they are about spending tens of millions of dollars on a series of trophy-hunting experiences by Jeff Novitzky."

U.S. Anti-Doping Agency chief Travis Tygart said those who make their living trying to game the system will never understand.

"Without Jeff and the many other dedicated law enforcement agents out there enforcing these important federal laws, the promise of sport fails our kids," he said.

A moment later, he added, "Our sports are the fabric of our American way of life. They teach us all that dedication, character, hard work, playing fair can lead to fulfillment and accomplishment. ... We do not tolerate this type of corruption and fraud in business, academia or other important institutions. Why should we accept it in sports?

"The answer is clear we should not," Tygart said.