The deaf officers, nicknamed the "Angels of Silence," are considered an asset because of their ability to read lips, to detect visual cues that might suggest nervousness or suspicious activity, and to pay attention to the visual periphery as they stare at a wall of monitors displaying different camera feeds.
If using sensory impaired people to fight crime sounds like the premise of a superhero movie, that’s because it is. In 2003 Ben Affleck starred in a film version of the Marvel Comics series "Daredevil," playing the title character whose remaining senses grow to superhero proportions after he is blinded by toxic waste. There is a precedent for the Oaxaca experiment in real life, too: In 2007 the New York Times ran an article about "a blind Sherlock Holmes"—a visually impaired Belgian man named Sacha van Loo whose acute sense of hearing and knack for identifying foreign accents over wiretaps has helped Belgian police combat terrorism and organized crime.
Update from a reader:
Mexico makes wonderfully creative use of disabled persons in security roles. Passing through the Mexico City airport recently we observed that many security people in uniform were wheelchair-bound: the ones who check your boarding pass and ID as you enter the security line, who answer questions at the information booths, etc. Obviously they also have quick and easy mobility to different areas of the airport. This seems like a progressive and humane practice and I don’t know why the US and many other countries haven’t imitated it.