Carlo Di Rienzi first appeared in Secret Six (DC, 1968 series) #1 (April-May 1968). He became the second Mockingbird in Action Comics Weekly (DC, 1988 series) #603 ([June 7, 1988]). Carlo was revealed to be Mockingbird in issue #628 (November 29, 1988), and he died in issue #630 (December 13, 1988).