ATLANTA --

Federal agents have expanded their investigation of pro wrestler Chris Benoit's personal doctor to include former patients and other patients of his who have died, and they seized records dated as far back as 2002, two years earlier than previously acknowledged, The Associated Press has learned.

An affidavit by a federal Drug Enforcement Administration agent that was part of a warrant to search Dr. Phil Astin's west Georgia office for a third time said investigators seized 68 boxes of documents, including patient records and billing statements, on Tuesday.

The affidavit said agents were looking for, in part, medical records of inactive or deceased patients, including medical tests, test results and physician notes.

The search followed a statement agents received last Friday from an unidentified source who was associated with Astin's practice and has known him personally for about 10 years. The source said files for former patients or patients who have died may have been stored in a copy room at Astin's office, the affidavit said.

The records "will be relevant and material to this ongoing investigation," the affidavit said, without elaborating.

Also seized from Astin's office, the affidavit states, were records of a Nov. 19, 2002, prescription for 200 mg of depo-testosterone, an injectable steroid, that was written for an unidentified patient. When Astin was charged last week with improperly prescribing medication to two patients other than Benoit, the indictment only referred to prescriptions dating to 2004.

A sheriff's official previously said that Astin also is being investigated in the February 2006 death of another wrestler, Michael Durham. State officials have not returned repeated calls in recent days seeking details on that case.

The disclosure about the expanded federal investigation follows word earlier this week that federal prosecutors plan to seek a superseding indictment against Astin.

A court filing Tuesday said that prosecutors have advised Astin's attorney, Manny Arora, that they will present the case to a grand jury for a second time "after a more thorough review" of documents seized from Astin's office in Carrollton. The filing did not say what charges will be sought in the superseding indictment or when the indictment will be sought.