ARMADA, Mich. -

Police investigators made their way to a St. Clair County landfill where they were looking for a specific piece of potential evidence in the April Millsap murder case.

What led detectives to the landfill is in itself concerning.

It all involves an unusual trash pickup made at the Vancallis family home in Goodells. It was a special trash pickup requested by someone calling from the home just days after the murder of April. The Vancallis family has had a contract with Jeff's Rubbish since 2010 to pick up their trash on the same day every week. However, the team from Jeff's got a call shorty after July 24 when April was killed. During the call a request was made for a special trash pickup.

After investigators learned about the special pickup, they tracked down the trash that was dumped and found a pair of shoes allegedly belonging to James Vancallis. Those close to the case say the tread on the shoes is similar to marks discovered on April's neck and chest.

The other key clue involves a fingerprint -- one discovered on April's cellphone. The phone was found not far from her body along the trail. It is still to be tested, but the Local 4 Defenders are told the fingerprint is not a match for April or her family -- who had their hands on her phone the day she was murdered?

The final clue is that small CC motorcycle, blue in color. It was located near the Vancallis family property in Goodells on Monday. It, too, is being tested for any possible clues. You may remember witnesses described seeing a similar bike near the trail the night April was killed.

While Vancallis remains locked up on unrelated drug charges, he has not been charged with any crimes connected to April's murder. However, it's clear investigators, who call him a person of interest, are working to learn everything they can about this man and what may have unfolded that day.

Police have investigated 800 tips since joggers found the 14-year-old's body July 24 in a drainage ditch along the Macomb Orchard Trail in Armada.