"When you look at the statistics on missing children, the longer it takes to find them - in all honesty - the lesser your chances of getting them back," Van Zandt said.
He thinks investigators are heavily-focused on Jessica's backpack, which was found Sunday morning about six miles from her home. Van Zandt says the backpack could offer hidden clues that go beyond DNA.
"Many times, we've seen abductors take a victim south and then drive north and dispose of an item ... trying to point investigators ... in the wrong direction," he said.
Van Zandt also says residents could play a key role in solving the case. He thinks a passersby who may have seen a commotion may have thought they were passing by kids playing, but now realize that it could be an incident involving Jessica.
Van Zandt also says that there are registered sex offenders in Jessica's neighborhood. He expects that investigators have been interviewing them.
He says that all hope is not lost, in terms of Jessica being returned home safely.
"If in fact she was taken by an unknown person, that person [may have] taken care of her and is trying to make a decision on when to return her to her family," Van Zandt said. He says police may urge the person to drop Jessica off at a fire station, police station or "anywhere where she could make a call ... and get back with her family again."
If you've seen Jessica Ridgeway or have a tip regarding her disappearance, call 303-658-4336 or email PDamberalert@cityofwestminster.us.
(KUSA-TV © 2012 Multimedia Holdings Corporation)