Gary Dunn, 28, entered the plea in a Russellville courtroom Monday morning. Dunn is charged in the 2005 slaying of Dirksmeyer, an Arkansas Tech student and former beauty queen. A gag order was issued in the case.
Dunn is being held on $1 million bond after being arrested last month in connection with Dirksmeyer's murder. An affidavit claims DNA evidence linked Dunn to the Dirksmeyer case.
Dirksmeyer's boyfriend, Kevin Jones, was tried and found not guilty last year.
Dunn's trial is now scheduled for April 13, 2009.