When David Jacobs, a personal trainer and supplement-store owner from Plano, Texas, pleaded guilty to steroid-distribution charges in November and agreed to cooperate with federal authorities, he told a local television station that he would offer evidence linking football players to performance-enhancing drugs.

Five months later, information from Jacobs has led authorities to subpoena at least one active NFL player — a member of the Atlanta Falcons — to testify before a federal grand jury in Texas, said two lawyers with direct knowledge of the matter. The player has not been publicly identified.

The lawyers also said that one of the subjects of the grand jury's investigation was Matt Lehr, an offensive lineman for the New Orleans Saints who played for the Dallas Cowboys from 2001 to 2004 and for the Falcons from 2005 to 2006. The NFL suspended him for four games in 2006 after he tested positive for a banned substance.

The lawyers said Lehr was being investigated for the suspected distribution of performance-enhancing drugs. The investigation is being led by the U.S. attorney's office for the Eastern District of Texas.

Distributors, not users, are often the targets of investigations into steroid use. In such investigations, the government frequently seeks the testimony of users — who often are athletes — to indict the distributors. In recent years, however, prosecutors have pursued athletes they believe have lied under oath, or to government agents, about their use of banned substances.

Paul Coggins, Lehr's lawyer, acknowledged his client was under investigation. But Coggins maintained that federal authorities had uncovered evidence that showed Jacobs had provided faulty information and that the investigation of his client would probably be dropped. Coggins said Jacobs had turned over Lehr's name to federal authorities only because Lehr refused to pay Jacobs' legal fees.

"He threatened Matt and said you have to pay my attorney's fees or I am going to end your career," Coggins said in a telephone interview on Saturday. He said Lehr met Jacobs when they were bodybuilders.

"Jacobs saw Matt as a guy with a lot of money and Matt declined to pay his fees," Coggins added.

Coggins, the former U.S. attorney for the Northern District of Texas, said he had represented Lehr for three months. "We are confident that the more the feds look at Jacobs, the less credible of a source of information he becomes," Coggins said.

In a telephone interview on Monday, Jacobs' lawyer, Henry E. Hockeimer Jr., said, "Mr. Jacobs has provided truthful, complete and corroborated information to the U.S. attorney's office."

Asked about Coggins' assertion that Jacobs was trying to get Lehr pay his legal fees, Hockeimer said, "That is certainly a strategy he could pursue at a trial, but it won't be successful."

The NFL, meanwhile, is cooperating with the government's investigation, according to Greg Aiello, a league spokesman.

In an e-mail message, Aiello did not say what the league's cooperation entailed. He also declined to say if league security personnel had reached out to Jacobs to learn more about what he told federal authorities.

An official at the U.S. attorney's office in the Eastern District of Texas declined to comment.

Jacobs was charged in September as part of Operation Raw Deal, a sprawling investigation led by the Drug Enforcement Administration that focused on dozens of suspected distributors of performance-enhancing drugs who were accused of purchasing raw materials from foreign countries.

Prosecutors made a deal with Jacobs, who was charged with seven others, in the hopes of obtaining more information about the distribution of steroids.

Before Operation Raw Deal, high-profile federal inquiries into performance-enhancing drug distribution appeared to be confined to the U.S. attorney's office in the Northern District of California, which has indicted 12 people over the past five and a half years as part of the Bay Area Laboratory Co-operative investigation and its offshoots.