Introduced as a rude, bigoted, incompetent bully who is universally disliked in the squadroom, he becomes the primary detective on the first of three murders for which both shifts are called in.

The character is rarely seen again for the rest of the season, but his limited screen time does establish that he holds a grudge against the Homicide unit in general, and against Russert in particular.

In the subsequent Season 4 episode, "The Hat", Gaffney is suddenly shown both as a lieutenant and as commander of his old evening Homicide shift, Russert's previous job.

His promotion surprises the unit, and upon his appointment, he issues thunderous orders about how Homicide was going to be run by the book under his command, citing among other things various small infractions of department rules that Giardello had chosen to overlook.

First, Gaffney was loyal to the chain of command throughout the department, and was willing to follow orders from above unquestioningly if it meant he could indulge his natural tendencies as a bully.

Gaffney is subsequently shown fulfilling his role as Harris' lapdog commander, often showing little to no moral objection to interfering with the Homicide Unit's investigations if ordered to do so for political reasons.

This is best seen in the Season 5 episode "Narcissus", in which Gaffney barges into an interrogation of a member of the African Revival Movement and insists on speaking to the suspect privately.

Gaffney came to Giardello requesting that Bayliss shut down the website which promoted bisexuality and Buddhism amongst other things or be subject to disciplinary action.