Sending Crime Underground

Police in Manchester have apparently foiled a planned robbery after the discovery of a tunnel heading towards a cash machine in a video shop.

What a completely genius plan - dig a tunnel all the way to the machine and then empty it underground before making a sharp exit.

Is it just me, or do the police seem a bit dimwitted for announcing they'd found it - wouldn't they have been better observing it whilst the would-be thieves continued digging, thus catching them red-handed?

Or is that too much like common sense?