ferret

Rachel was sitting at her window, keeping a sharp eye on everything that passed, from brooks and children up, and that if she noticed anything odd or out of place she would never rest until she had ferreted out the whys and wherefores thereof.

He was a strange little ferret-like man, with white eyelashes, and when I looked up at him I found his keen grey eyes fixed upon me with an amused expression.

Lestrade, lean and ferret-like as ever, was standing by the doorway, and greeted my companion and myself.

I therefore organized my Street Arab detective corps, and sent them systematically to every cab proprietor in London until they ferreted out the man that I wanted.