If he's innocent though & genuinely doesn't know here wear-abouts, will he just give any answer the police want, to stop the torture, thus sending them on a time wasting wildgoose chase?
I agree, and as you said, the family are not to blame, you should be able to let your kids play unsupervised, but parents have to face reality, we do not live in Utopia & this sort of thing will happen from time to time. Our 11 (nearly 12) year old has to be in before dark. Paranoid, possibly, but hopefully sensible as well.
Unfortunately, I cannot see this ending well.