The first person in the country to be convicted of using Limewire and other file-sharing software to steal identities has been sentenced to more than four years in prison.

Gregory Kopiloff, 35, pleaded guilty in November to federal charges of mail fraud, accessing a protected computer without authorization to further fraud, and aggravated identity theft.

At sentencing U.S. District Judge James L. Robart called Kopiloff "a highwayman in the virtual world," the U.S. Attorney's Office said in a news release.

Although people have been prosecuted for using networks to illegally share copyrighted music, movies and software, the Justice Department called Kopiloff's prosecution its first case against someone accused of using file-sharing to commit identity theft.

Using the file-sharing programs, Kopiloff searched people's computers for personal financial documents, such as federal income tax returns, student financial aid applications, and credit reports. In many cases, prosecutors said, Kopiloff's victims were unaware their children had installed the software on home computers.

"Kopiloff's techniques were not 'run of the mill' identity theft," Assistant U.S. Attorney Kathryn Warma wrote. She described his techniques as "particularly pernicious and devious."

Kopiloff's attorney, Jennifer Wellman, argued for three years in prison, saying her client regretted his actions and had turned to identity theft to support his drug and gambling addictions.