Quoted:
First thing you do if you think there is a prowler on your property is call 911. Just that one phone call can keep this from happening again. If you really want to go outside to check it out after that, at least if there is a cop prowling around your private property you both might know it.
vice versa. The cop should inform the property owners, that he'll be patrolling that night (it was by request of property owners there).
Make friendly so they know each other face to face and verbally.
Dark conditions, a "drop your gun, I'm a LE" command is dubious.