"I believe that he’s stashed," Young told PEOPLE on Tuesday. "I believe it's the investigation that's going to lead us."
The missing Oregon boy's father, Kaine Horman, echoes his ex-wife's belief that they will bring the 7-year-old home safely.
"Someone is going to spot him. We're going to get him," says Horman, though he adds he and Young have been stressed and frustrated because "it shouldn't have to take a while. It should be done by now."
They also suspect Kyron's stepmom, Terri Moulton Horman, planned his abduction and knows where Kyron is.
Young says Terri has "the big answer."
"I think it [was] arranged," adds Kaine. "We have no information that would lead us to believe that, but I think based on what Desiree and I know about [Terri], I think it's a plan. And I think she's still executing a plan."