Federal prosecutors have achieved their first guilty plea and prison sentence in the Megaupload criminal case that has dragged on for over three years.

Andrus Nõmm—who was arrested this week in Virginia after years of fighting extradition in the Netherlands—pleaded guilty to felony copyright infringement. He was sentenced to a year and a day in federal prison, according to a press release issued by the Department of Justice on Friday.

“This conviction is a significant step forward in the largest criminal copyright case in U.S. history,” Assistant Attorney General Caldwell said in the statement. “The Mega conspirators are charged with massive worldwide online piracy of movies, music and other copyrighted U.S. works. We intend to see to it that all those responsible are held accountable for illegally enriching themselves by stealing the creative work of U.S. artists and creators.”

American criminal charges against the six co-defendants related to Megaupload, including Kim Dotcom, still remain pending. All of the Megaupload defendants (most notably founder Kim Dotcom) have been battling extradition and fighting the government's case from outside US borders. (Ars profiled Dotcom’s extradition efforts last month.)

On Twitter, Dotcom wrote:

The US Justice system: An innocent coder pleads guilty after 3 years of DOJ abuse, with no end in sight, in order to move on with his life. — Kim Dotcom (@KimDotcom) February 13, 2015

I have nothing but compassion and understanding for Andrus Nomm and I hope he will soon be reunited with his son. — Kim Dotcom (@KimDotcom) February 13, 2015

Prosecutors also added that Nõmm “agreed to waive his extradition hearing in the Netherlands, where he was arrested in January 2012, and plead guilty in the United States.”

The statement continued:

In court papers, Nomm agreed that the harm caused to copyright holders by the Mega Conspiracy’s criminal conduct exceeded $400 million. He further acknowledged that the group obtained at least $175 million in proceeds through their conduct. Megaupload.com had claimed that, at one time, it accounted for four percent of total Internet traffic, having more than one billion total visits, 150 million registered users and 50 million daily visitors. In a statement of facts filed with his plea agreement, Nomm admitted that he was a computer programmer who worked for the Mega Conspiracy from 2007 until his arrest in January 2012. Nomm further admitted that, through his work as a computer programmer, he was aware that copyright-infringing content was stored on the websites, including copyright protected motion pictures and television programs, some of which contained the “FBI Anti-Piracy” warning. Nomm also admitted that he personally downloaded copyright-infringing files from the Mega websites. Despite his knowledge in this regard, Nomm continued to participate in the Mega Conspiracy.

Nõmm's attorney, Alan Yamamoto, did not immediately respond to Ars' request for comment.

In a comment sent to Ars by text message, Ira Rothken, Dotcom's chief global counsel, wrote: