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Exposure to a chemical (or radiation, or some other toxin). All the suspects are in a particular area, or do a particular task, but only the murderer gets exposed to the MacGuffinium. The suspect...
Answer
#4: Attribution notice removed
by
System
·
2019-12-13T12:00:27Z (over 4 years ago)
Source: https://writers.stackexchange.com/a/15851 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#3: Attribution notice added
by
System
·
2019-12-08T03:57:52Z (over 4 years ago)
Source: https://writers.stackexchange.com/a/15851 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
**Exposure to a chemical (or radiation, or some other toxin).** All the suspects are in a particular area, or do a particular task, but only the murderer gets exposed to the MacGuffinium. The suspects are screened in some manner, and the murderer submits to the screen, thinking all evidence has been cleaned away (using normal methods), but the screen which the protagonist uses is a level or two up, and picks up the contamination. Not a precise example of this, but close, in _House, MD,_ in the episode ["Clueless"](http://house.wikia.com/wiki/Clueless): The wife was poisoning her husband but didn't know the poison would leave a chemical trace on her hands, and House was able to use something to demonstrate the poison on her hands. On the _Agent Carter_ episode "Bridges and Tunnels:" > Carter is exposed to radiation from an explosion, and realizes that her watch absorbed more of the radiation than her clothes and skin. When one of the bad guys comes up in the line but doesn't ping, she suggests that his locker, including his street clothes and watch, should be scanned. Bad Guy bolts.
#1: Imported from external source
by
System
·
2015-01-12T11:13:19Z (over 9 years ago)
Original score: 1