Jury selection began Tuesday. Friday started with 61 potential jurors in the pool. That number has been dwindled down to the final 12 jurors and two alternates.
Willis, 48, is accused in the April 2013 kidnapping and murder of the Norton Shores convenience store clerk. He is charged with open murder and kidnapping.
Willis was convicted last year for the 2014 murder of Rebekah Bletsch.
Court officials said they worked to find people who can hear the Heeringa murder case impartially.
The judge plans to have attorneys deliver their opening statements on Tuesday, May 8.