A man was sentenced to more than four years in prison Monday in what prosecutors said was the first federal case against someone using file-sharing software to steal identities.

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

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 programs such as LimeWire to commit identity theft.

Kopiloff, 35, of Seattle, used the software to search people's computers for personal financial documents. In many cases, prosecutors said, Kopiloff's victims were unaware their children had installed the software.

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

"The judgment in Seattle shows that there are people out there who are working to exploit this information and use it to commit fraud," comments IFPI chairman/CEO John Kennedy, noting that the federation offers free Digital File Check software which can disable peer-to-peer networks on users' computer.