IMO, not necessarily. It's difficult to fully get rid of all trace forensic evidence of crimes, but it's easy to miss if the police don't know exactly what they're searching for or where to look for it. They may well be finding other evidence that's allowed them to narrow their focus considerably, and the vehicles particularly stand a good chance of holding some evidence, since if Gus isn't there and didn't wander off on his own, someone would have needed to transport him a significant distance (if he vanished from the homestead in the first place). Also remember, other adults live there, not just the suspect, and right now the suggestion is neither were involved. If true and the other two were both kept completely in the dark, depending on what happened it could be hard to do the kind of evidence-destroying deep clean needed to really scrub all traces away without them noticing, say, a strong odor of bleach. And if not completely true and someone acted as an accomplice in a cover-up, that's someone who might be more likely to have a change of heart and tell LE what they know (say, divided loyalties between your partner and your grieving daughter; additional evidence, increasing pressure from LE, or even just time can shift the balance from one to the other).
If this is in fact a major crime and he didn't wander off, that means at least one person knows where he is, and people can be persuaded to give up secrets like that with the right leverage, particularly when LE are able to collect enough evidence for prosecutors to make a solid case even without a body (often a reduced sentence in exchange for revealing the location). Once again, MOO, but it sounds like they have lines they're actively pursuing and not stymied at a dead end right now. That means there's still a real chance to find him, find out what happened, and pursue justice as warranted. Here's hoping they do.
Absolutely. The same for not taking them to a hospital when they're badly hurt or sick but still could be saved if they got medical attention in time.
