Diedrich and Harris are first seen investigating a homicide at Veronica Deane's mansion. The two talk about both Deane and the homicide for a bit before going inside to question the staff about the murder, the victim being Sterling Archer.
When Lana Kane tries to get a recommendation letter for Abbiejean Kane-Archer to go to "pre-pre", the cops end up getting called on her. Diedrich is the one who arrests her, noting that, among other things, she had what appeared to be a very crudely drawn vagina pass.
When the hostage situation at Ellis Crane's mansion got out of control, Diedrich and Harris try to come up with a way to rescue the hostages. They try negotiating with the leader of the attackers, Mr. Rompers, in a number of ways (including offering them pizza), but he turns them all down, telling them that if the phone rings a hostage gets executed. Eventually, Mr. Rompers gets tired of the situation and goes into "Plan X", which involves disguising the hostages as clowns and escaping with their clown outfits off, and the LAPD storms the mansion and beanbags the hostages.
"You shut up! Shut your mouth, or I swear to Christ in his Heaven I will personally frame you for this murder!" "Hey, bub, remember? About the thing?" "Please disregard my previous statement. Merely an ill-advised attempt at levity."
After Ellis Crane was murdered, Diedrich and Harris showed up on the set of Crane's film Deadly Velvet, where they declared that there was an active homicide investigation going on, and that while the investigation was going on, none of their persons of interest (Sterling Archer, Lana Kane, Cyril Figgis, Malory Archer, Ray Gillette, Pam Poovey, Cheryl Tunt, Dr. Algernop Krieger, Veronica Deane, and Alan Shapiro) were to leave town without checking with the two. Malory claimed that nobody present could have murdered Ellis Crane, since he hired them for protection, and they think that Crane could have been caught up in some insurance fraud; Diedrich told her that they would be looking into all that. Sterling told him that everyone there has an alibi, Diedrich tells them that they have nothing to worry about, and Harris tells them that they have an exact time of death (since Crane had a defensive wound on his body which went through a watch on his wrist): 2:14 P.M. Veronica Deane realizes that she and Sterling are innocent, since they were together until "almost the stroke of three."
"Hey. Yeah, I-I need you to come back to the studio real quick. No, the van's not here, but it looks like we've got another homicide s... uh... just in the very brief time since you left, yes." "What, are you shootin' 'em yourself?"
Diedrich and Harris' names may have come from Detective Arthur Dietrich and Sgt. Ron Harris, characters on the police comedy Barney Miller, which ran from 1975 to 1982.
A common rumor concerning Harris was that Diedrich called him "Bob" (assumed to be his real name) while trying to calm him down. However, Diedrich actually said "bub", which is one of Wolverine's most famous phrases.