Record companies can prove that Jammie Thomas-Rasset's computer was used to download copyrighted files, an expert testified Tuesday, but her attorney contended that doesn't prove that she was clicking the mouse at the time.

As Thomas-Rasset's retrial in Minnesota federal court continued, recording companies spent the day presenting evidence they said will prove she is guilty of illegally downloading and distributing more than 1,700 songs through software she said she hadn't even heard of until the lawsuit.

Thomas-Rasset, of Brainerd, Minn., who owns close to 300 CDs and did a case study on Napster in college, took the stand to defend herself for a second time against claims by the Recording Industry Association of America (RIAA) that she illegally downloaded and distributed 1,702 songs through Kazaa, an online file-sharing network.

Her original 2007 trial and this week's retrial are the first cases to go to a jury trial in a recording company campaign of more than 30,000 suits against alleged copyright infringers.

Judge Michael Davis granted a retrial because he had given incorrect instructions to the jury. He had told jurors that they should consider it copyright infringement simply if somebody makes the music files available to other users. But Davis, after reviewing the case, decided that others would have had to actually download the files in order for infringement to have occurred.

The jury found Thomas-Rasset liable in the first case and ordered her to pay $220,000 in damages, but it will be harder to prove that others downloaded the songs that allegedly came from her computer; there is no way to tell who, if anyone, has downloaded a file from a shared folder on Kazaa.

Doug Jacobson, a computer network expert held on retainer in more than 300 of the RIAA's cases against alleged copyright infringers, testified that someone at Thomas-Rasset's computer was guilty of downloading, as evident by the fingerprints her Internet Protocol address and modem number left on the downloaded files. That is consistent with the findings of an investigation done by MediaSentry, a company hired by the record companies to find information on file-sharers.

But Jacobson agreed when defense attorney Joe Sibley said the screen shots that capture that data can't prove who was sitting at the computer and downloading the songs.

"Not the physical human being," Jacobson said.

When Thomas-Rasset took the stand, she continued to deny that she had ever used Kazaa to download a song. RIAA lead attorney Timothy Reynolds asked Thomas-Rasset, who admits she likes many of the songs she allegedly downloaded and had a working knowledge of peer-to-peer file-sharing, if she had used Kazaa before the lawsuit.

"I had never heard of Kazaa," Thomas-Rasset replied.

The RIAA spent most of Tuesday trying to prove that Thomas-Rasset covered up her illegal downloading by swapping out her computer hard drive in 2005 before the record companies could subpoena it.

Duluth Best Buy Geek Squad manager Ryyan Maki testified that Thomas-Rasset had her hard drive replaced after she learned the RIAA was going to sue her. Under cross-examination, he said the hard drive must have been truly defective, not simply swapped out, or Best Buy wouldn't have replaced it under its warranty policy.

Today, the recording companies are expected to bring their last witnesses to the stand. The defense said it will probably call Thomas-Rasset again before its closing remarks.

Alex Ebert • 612-673-4264