Source : Webster's Revised Unabridged Dictionary (1913)

Searching \Search"ing\, a.
   Exploring thoroughly; scrutinizing; penetrating; trying; as,
   a searching discourse; a searching eye. ``Piercing,
   searching, biting, cold.'' --Dickens. -- {Search"ing*ly},
   adv. -- {Search"ing*ness}, n.

Source : WordNet®

searchingly
     adv : in a searching manner; "`Are you really happy with him,'
           asked her mother, gazing at Vera searchingly"