Was there a serial downloader lurking outside Jammie Thomas' window? Did someone else hook up a computer to her Internet connection?

Those are some of the questions her attorney has been raising in the nation's first trial of someone accused of illegally sharing music online.

But Richard Gabriel, lead attorney for some of the nation's largest record companies, sought to pick those ideas apart one by one by calling witnesses to document each step the record companies used to point the finger at Thomas.

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Testimony in the civil case was to resume Wednesday in federal court in Duluth. The case could wrap up as early as Wednesday night or Thursday.

On the courthouse steps Tuesday, Thomas denied illegally downloading music. In court, attorney Brian Toder has said there's no proof she shared music illegally.

Toder's cross-examination has focused on raising doubt about whether the record companies can really prove it was Thomas who downloaded and shared the 1,702 songs, as the record companies allege she did in 2005.

He suggested in his questioning that someone other than Thomas — someone outside her window, or a neighbor — could have been responsible if she used a wireless router. That could have allowed anyone nearby to utilize her Internet connection, using the same address that led the record companies to Thomas.

The companies have backed up their claims with literally a wall of data — enlarging printouts of logs and dates and Internet addresses on a screen in front of jurors, with Gabriel zeroing in with a laser pointer to highlight the entries he says prove Thomas did what they say she did.

Mark Weaver of SafeNet Inc. testified about how his company, at the behest of the record companies, found 1,702 songs offered by a user of the Kazaa file-sharing program under the name "tereastarr."

Then defense attorneys put on David L. Edgar of Charter Communications, Thomas' Internet provider. He testified about how he and another investigator independently matched the Internet address used by tereastarr to both Thomas' account and an electronic address for the cable modem she leased from the company.

Doug Jacobson, a computer security expert and professor at Iowa State University, testified that Toder's theory that someone else used a wireless router to download the songs linked to Thomas was far-fetched. He said records subpoenaed from Charter don't show the kind of Internet address used by such routers.

"There was no wireless router used in this case," he said.

Thomas, a 30-year-old mother of two from Brainerd, is expected to testify during the trial.

"I do know that I didn't do this, and the jury will hear that I did not do this," she said Tuesday outside the courtroom.

Thomas' computer hard drive will be a key to the case. She and her attorney say she replaced it at the suggestion of Best Buy Co. after she had some computer problems in 2005. The record companies say she was trying to cover her tracks after they sent her messages saying she was illegally distributing their files.

Music sales have slumped in recent years as more people have turned to file-sharing. The Recording Industry Association of America, which is not a party to the lawsuit, says record companies have brought more than 26,000 actions against people alleging they shared files in violation of copyrights.

The action against Thomas is the first to get to trial because most defendants have settled by paying a few thousand dollars.

Jennifer Pariser, head of litigation and antipiracy at Sony BMG, portrayed the trial as a fight for survival.

"It is imperative for Sony BMG to combat this problem," Pariser testified Tuesday. "If we don't, we have no business anymore."

In response to a question from Toder about whether the industry was making millions off all the settlements, Pariser said the campaign has actually lost money.

Thomas, who works for the Department of Natural Resources of the Mille Lacs Band of Ojibwe, is at risk for a judgment of more than $1.2 million if jurors found against her for all 1,702 songs. The recording association is seeking damages set under federal law of $750 to $30,000 for each copyright violation.

Besides Sony BMG, the companies that sued Thomas are Arista Records LLC, Interscope Records, UMG Recordings Inc., Capitol Records Inc. and Warner Bros. Records Inc.