San Francisco ? Federal prosecutors obtained Barry Bonds’ medical files as part of their investigation into whether the slugger perjured himself when he said he never knowingly used steroids, a newspaper reported Saturday.

Two people familiar with the probe told the San Francisco Chronicle that the U.S. Attorney’s office received the medical records Wednesday in response to a subpoena issued to the San Francisco Giants. The sources requested anonymity because of the investigation’s sensitivity.

U.S. Attorney Kevin Ryan said Thursday his office still was pursuing an “ongoing steroid-related investigation” even though a federal grand jury considering possible perjury and tax-evasion charges against Bonds expired that day without an indictment.

A new grand jury is expected to be impaneled this Thursday.

Ryan said he had postponed his decision on whether to seek an indictment of Bonds “in light of some recent developments.” The receipt of the medical records was one of those developments, sources told the Chronicle.

The records are believed to include information about three operations Bonds had last season to treat his right knee, as well as a serious elbow injury that required surgery in 1999, the newspaper reported.

Bonds’ former girlfriend, Kimberly Bell, testified that Bonds blamed the elbow injury on steroid use, the Chronicle reported.

Prosecutors subpoenaed the documents nearly two months ago, but Bonds’ attorneys went to federal court to stop the government from obtaining the records. Prosecutors prevailed Tuesday and received the documents a day later.

“I am confident and certain that the records at issue will completely undermine any claim that Barry has used steroids at any time in his entire baseball career,” Bonds’ attorney, Michael Rains wrote Friday in a statement e-mailed to the Chronicle.

Giants general counsel Jack Bair declined to comment.

At least three of Bonds’ surgeries were performed by Dr. Arthur Ting, who testified in the government’s perjury investigation and turned over his own medical records on Bonds, the Chronicle also reported.

The seven-time NL MVP is being investigated for allegedly lying to a federal grand jury investigating the steroids conspiracy case involving the Bay Area Laboratory Co-Operative.

In sworn testimony in December 2003, Bonds said he never knowingly took banned drugs.