A renewed push to solve the 2001 murder of federal prosecutor Thomas Wales prompted me to look back through KING 5's files for any material related to the case.

Before KING moved from its building on Dexter Ave. to new studios across from Safeco Field, I was packing up tapes and discovered this -- the raw footage from a story that never aired.

Nearly 20 years ago, I was on the federal court beat, and one day I dropped in on an arraignment in a complex and confusing case involving military helicopters. The tape I came across in my files shows what may have been a fateful day in the life of Tom Wales.

The video was shot on October 12, 2000, at what was then the federal courthouse on 6th Ave. in Seattle. In it, you see me trying to convince two of the defendants to talk to me.

Minutes later, assistant U.S. attorney Tom Wales walks out (he's the man wearing the tie in the video). Wales was the prosecutor who charged four men with illegally altering Vietnam-era helicopters for use by logging companies and firefighters.

Wales did not comment that day. But after Wales was killed in his home a year later, one defendant in the case became the focus of one of the most intense FBI investigations ever.

One of the men you can see in the October 2000 tape is Bob Chadwell, an attorney who represented one of the defendants in the case. The government claimed the four men, two of them owners of a company called Intrex Helicopters, were breaking the law because the military-grade helicopters could not qualify for civilian use in the United States.

"You couldn't get an airworthiness certificate for one of these rebuilt helicopters and therefore it was dangerous and unsafe for these helicopters to be used," Chadwell said, summarizing the government's case.

But the prosecution fell apart when an FAA witness testified that the helicopters were in fact safe. The result was that the government reduced some charges and dismissed others.

Yet one of the defendants -- not Chadwell's client -- was so upset by the case being brought that he tried unsuccessfully to sue Wales for malicious prosecution.

"He was clearly not a happy man," Chadwell said of the man.

FBI sources have also said they believe the defendant was upset by Wales anti-gun policies as the president of Washington CeaseFire.

KING has not named that other defendant because he's always denied involvement in Wales's murder. And ever since the 2001 murder, he's never been arrested or charged, though his home has reportedly been searched more than once by federal agents.

At a Wednesday press conference in Seattle, federal officials said the same thing they've said for nearly 17 years: The Wales case remains a large-scale and active investigation. Investigators said the total reward -- a mix of government funds and money raised by the National Association of Former United States Attorneys -- is now more than $1.5 million. They believe Wales was possibly killed by a hit man who was working for a small group of individuals.

-- Follow Chris Ingalls on Twitter: @CJIngalls