It's been more than three months since Grade was found dead in her driveway and still, police are trying to find out who killed her, and why.
They say Kevin Zarm might know something about that.
But before any serious action can be taken up against him, they need good, hard proof.
"We've certainly put a lot of material together, but we're waiting for that one piece of teriffic evidence that would make a case for us," says Wausau police chief Bill Brandimore.
So far, all of what they have is circumstantial.
In Zarm's preliminary hearing Wednesday, an officer testified that Zarm was in the neighborhood at the time of Grade's death.
And Brandimore says there are residents of that area saying the same thing.
"We've documented through witnesses that accompanied him to the area, that we can place him there in a time that's interesting for us."
But until that one incriminating piece of evidence comes up, Zarm will most likely remain a person of interest, not an official suspect.
Brandimore says there's not enough proof to to the D.A. with anything yet.
He adds that there are no other persons of interest in this case.