Green’s Dictionary of Slang

co-d. n.

[abbr.]

co-defendant.

[UK] in R. Graef Living Dangerously 189: Even when my co-d (co-defendant) wasn’t a mate I wouldn’t do it [i.e. inform].
[UK]G. Krauze What They Was 262: The last [female prison officer] got caught giving his co-d brain in his cell.