On May 18, 2010, CBS announced that the series had been canceled. The series aired in syndication, and also on Ion Television in the U.S. and on Viva in Canada. Sleuth also aired the series occasionally. In 2011, the show aired on MyNetworkTV.
Due to the use of contemporary music in each episode, none of the seasons are presently available on DVD, due to music licensing issues. However, the entire series, incorporating the contemporary music, was previously released on DVD as Cold Case: The Complete Edition, by CBS Productions (ISBN 8-5857-9659-6), on 44 dual-layer disks, in a single boxed set. This set is out of print.
The show is set in Philadelphia, Pennsylvania, and follows Detective Lilly Rush (Kathryn Morris), a homicide detective with the Philadelphia Police Department, who specializes in "cold cases", or investigations which are no longer being actively pursued by the department. Rush was initially partnered with Detective Chris Lassing (Justin Chambers) in the first five episodes and then with Detective Scotty Valens (Danny Pino) for the remainder of the series. They work under Lieutenant John Stillman (John Finn) and are assisted by other detectives from their squad—Nick Vera (Jeremy Ratchford), Will Jeffries (Thom Barry), and beginning in season three, Kat Miller (Tracie Thoms).
Usually, each episode would focus on a single investigation. All cases involved murders committed in Philadelphia, although investigations occasionally required travel outside the city. Cases were also spread out over much of the previous century, with some as recent as a year or two old and others dating back to the 1910s. Generally, an investigation would begin when the police received a new lead, or "new direction", on a case. This might be the discovery of a body, a new lead such as an alibi witness not found in the original investigation, new evidence pointing to the innocence of the accused, or a critical piece of evidence such as a murder weapon (e.g., one investigation began when a gun received in a gun buyback program was linked to a murder through ballistic evidence). In some cases, the lack of a body meant that it was originally unclear if a crime had even occurred, with people instead believing that the victim had merely left town.
Over the course of the episode, the detectives would interview witnesses associated with the crime and piece together the story of what led the victims to their death. These interviews were accompanied by flashback sequences to the time of the murder which dramatized the testimony. Witness testimony, even from people who would later be revealed as the killer, was almost never false. At most the guilty party would lie by omission, leaving out critical details, or stopping their narrative before they implicated themselves. The witness testimony was also generally presented in chronological order so that it formed a cohesive linear story for the audience.
The show was also distinguished by "double casting" in which the characters and witnesses would flash back and forth in the scene representing them as they looked at the time of the crime and in the present day. This was done with different actors as children or much younger selves especially if the year in question was well in the past. If it was judged that the character was not likely to have altered in appearance significantly except for weight and gray hair, the same actor would be used. This was not just with the guest actors themselves but sometimes with the detectives as well if they had any involvement in the original investigation. Detective Jeffries for example had flashbacks to himself as a child in two episodes and a young detective in another. Sometimes the twist in the story is that the prime suspect is the most obvious suspect
At the end of the episode, when the killer/s were exposed and confronted the confession would be in a flashback scene depicting the murder. The scene would show the details with exceptions having to do with the utter heinousness of the underlying motive of the crime such as rape or sexual assault. The police would be shown arresting the killer and walking them into custody. The killer and other characters in the story would be seen as flashing back to their younger selves and as now. The spirit of the victim would be seen either by Lilly, one of the other detectives or a loved one of the victim. This would be accompanied by the playing of a song meant to symbolize the period in which the killing took place.