Usher

Usher was a San Francisco police officer on duty during Day 3.

Day 3
Usher was part of a team which disabled a contagion-dispersal device carrying the Cordilla virus, which was seized from one of the virus couriers of bio-terrorist Stephen Saunders. In Los Angeles, Jack Bauer was patched through Usher's colleague, Roger Sommers to get directions on how to disarm a similar device captured from another courier, which was attached to the arm of Chase Edmunds. Sommers gave directions, but had to stop when the timer on the device didn't stop.

Sommers then signaled Usher to come over to help. Usher analyzed the device diagram on the computer screen and confirmed to Sommers that the two devices were indeed didn't match. Sommers then told Jack not to do anything else until he and Usher can figure out the issue and hung up the phone. Jack could not wait for Sommers to call back, and instead used a fire ax to chop off Chase's hand and isolate the device.