fishing expedition An investigation conducted without definite purpose, plan, or regard to standards of propriety, in hopes of acquiring useful (and usually incriminating) evidence or information; apparently aimless interrogation designed to lead someone into incriminating himself. This expression refers to the literal fishing expedition in which, armed with basic equipment, one goes after his prey without knowing exactly what, if anything, he will catch. The more skillful and experienced the fisherman, though, the better are his chances of successfully catching his quarry.

go over with a fine-tooth comb see THOROUGHNESS.

leave no stone unturned See THOROUGHNESS.

shakedown A thorough search, as of a prison cell in hopes of finding hidden weapons or other contraband. This expression alludes to shaking a tree to expose and acquire fruits or nuts which might be hidden within the foliage, and implies that something is turned upside-down and shaken to reveal the desired items. The expression is often used as a verb, to shake down.

As an adjective, shake-down is often applied to a cruise or flight undertaken to expose any mechanical flaws and to orient the crew while breaking in and adjusting the new equipment. See also shakedown, EXTORTION.

take soundings To investigate, to try to find out what is going on or how things stand; to psych out a situation. To take soundings is literally to measure the depth of water by letting down a line with a lead attached to the bottom. Figurative use of sounding appeared in print during the time of Shakespeare.

the third degree Intensive, prolonged interrogation, often in conjunction with physical abuse, to obtain information or force a confession. Usually used in the context of a prisoner’s being questioned by the police, third degree refers to the severity of the techniques employed. Just as a third-degree burn is the most damaging and extreme type of burn, so is a “third degree” the most drastic form of interrogation.