Doyle Investigations began on the WB episode following the Angel episode Hero of which Doyle sacrificed himself to save the half-blood demon innocents of the episode and Angel and Cordelia Chase. Writer Ja n-Eric Pietralla approached the character of Doyle and actor Glenn Quinn to reprise the role in his own television series following the short lived existence of Doyle on Angel. The show was then accepted and put into production by the WB and aired on April 1st 2000. The first and only season begins with the pilot episode City of Doyle taking great aim from Angel's premiere City Of.