sleuthhound

noun

1. A working dog who tracks or pursues e.g. a wanted criminal; a bloodhound formerly used in Scotland.

   “Sometimes he pursued the wily burn trout with relentless ferocity and the silent intentness of a sleuthhound. Often, however, he would pause and with his finger indicate some favourite stone to Winsome.”

2. (informal)A detective; a sleuth.

   “And straightway the minions of the law led forth from their donjon keep one whom the sleuthhounds of justice had apprehended in consequence of information received.”

   “Of course, that may be an accident and couldn't possibly be called a case against anybody; but then we haven't the means to make a real case against anybody. Till the police come we are only a pack of very amateur sleuthhounds.”