What entity do you think would be best to find someone who is somehow concelaing their presence?
Most people don’t know how to hide themselves on a causal level, instead masking and hiding, or altering their energy signature, and the energetic tethers they create between people and places.
You could sense them out by tracing the causal threads that are woven in the events of their daily lives. Simply tell your mind to “highlight” the appropriate thread of causality that will lead you back to their “current” spacetime location. You might sense the thread stretching off into the distance when you zoom in on it, just tell yourself to move to the end.
To see the web of causality and interact with it simply project to the 5th dimension of causality. To do this take the dimensional directions of space and time you know, and move “inwards” from the 4th dimension of time to that 5th dimension which brings the various aspects/threads of events together to be played out temporally.
Let your inner self absorb the technique and go by instinct.
I know it is not what you asked, but this might prove to be more useful in the long run. 
EDIT:
If when you get to the end and you do not “see” them use a bolt of energy to shatter their cloaking spell. If that doesn’t work, and it is an illusionary spell they are using, shatter it as you would shatter a mirror.
I havent tried projecting there before. Does sound interesting though, but this sounds like its some pretty advanced projection techniques. Wish I had more control on getting out and staying out, if I did I know someone who could most likely help walk me through doing all this.
Just use mental projection, or “scanning” it is a lot easier, very similar to visualization, except the images/information arise spontaneously, without your conscious effort.
As a basic intro, simply visualize your town from above. Tell your mind to light up the leylines or flows of the earths energy in your area.