Mitchell (undisclosed) left practice early Wednesday and did not return, Brooks Kubena of The Athletic reports.
Per Christiaan DeFranco of The Daily Local News, Mitchell was shaken up after a one-on-one drill with wide receiver Hollywood Brown, but the precise nature of the injury is still unknown. If Mitchell misses more time, Kelee Ringo would be a candidate to fill the vacated reps with the first-team defense.