Born in Minneola, Kansas, Melgren received a Bachelor of Arts degree from Wichita State University in 1979 and a Juris Doctor from Washburn University School of Law in 1985.
[2] In 2008, Melgren prosecuted the tax avoidance firm Renaissance, The Tax People for defrauding its clients out of at least $84 million, and secured a twenty-five year sentence against the firm's founder, Michael C.
[4] Melgren was nominated by President George W. Bush on July 23, 2008, to fill a seat in the District of Kansas vacated by Judge Monti Belot.
[5] He was confirmed by the United States Senate by a voice vote on September 26, 2008, and received his commission on October 6, 2008.
[6] On January 3, 2022, the United States Court of Appeals for the Tenth Circuit held that it was "procedurally unreasonable" for Melgren to impose a harsher sentence on a defendant because she had pled guilty without reaching a plea agreement with the prosecution.