What would you do? New hire may be a thief

Imagine this situation: A few employees have reported personal items missing from their workspaces — and it all began shortly after a new employee started.
Obviously, most people are blaming the new guy — but there’s no proof.
Furthermore, his background and references were thoroughly checked and came up clean. But that’s not enough for his new manager and co-workers, who want some action to be taken right away.
We asked three HR managers how they’d handle the problem:
Response #1: We’d address the issue in our employee newsletter — without pointing fingers at any specific employee. We’d just remind people not to leave valuables unattended. Raising awareness might be enough to stop future thefts.
Response #2: It sounds like we need to conduct a thorough investigation before deciding the new guy was to blame. I’d ask the victims where and when the items were taken and find out who would’ve had access to those areas at those times. Then I’d interview all the suspects to see what I could find out.
Response #3: First, I’d make sure a thorough background check was completed before the new employee was hired. Then I’d ask the manager to keep a close watch on him — without making accusations. It certainly sounds like the new guy is to blame, but we can’t take any action just yet.
If you were in the situation, what would you do? Let us know by leaving a comment below.