The third season of Criminal Minds premiered on CBS on September 26, 2007 and ended May 21, 2008. The third season was originally to have featured 25 episodes; however, only 13 were completed due to the Writers Guild of America strike. Seven more episodes were produced after the strike, bringing the total number of episodes to 20 for the third season. Mandy Patinkin wanted to leave the series, since he loathed the violent nature of it. He was replaced by Joe Mantegna several episodes later.
The team investigates a serial killer who is targeting women at a small college in Flagstaff, Arizona. The BAU shuts down the campus, creates a detailed profile of the unsub, and arrests a suspect. However, the team members begin to have doubts about themselves when another woman is killed while the suspect is in custody.
In Milwaukee, a series of women have been found murdered with their hearts crudely removed. The BAU is assigned to the case, but they are short three members: Gideon, who is missing, Hotch, who is on suspension and Prentiss, who resigns her commission to join the Foreign Service. Supervisor Strauss steps in as lead, but she doesn't handle herself well in the field.
The BAU travels to Portland to assist local authorities in investigating the disappearances of people who are new to the city and have no strong social ties.
When home invasions involve the murder of entire families, the BAU is called to Denver to identify the killers who possibly have been abused while in foster care.
The investigation turns to the family as the BAU and local authorities race against time to locate a young girl who has disappeared from a local shopping mall.
Halloween provides the scenario when the BAU is called to Dallas to assist in the investigation of women who became victims of a man they'd met through a dating service and then rejected him.
SSA David Rossi returns to the BAU from retirement as the team is called to Montana to investigate the case of four kidnapped and murdered women. When another woman disappears, the search leads to a man who apparently has assumed the identity of his dead partner.
A team member's life is put in jeopardy when the BAU investigates serial killings in Florida that appear to involve the occult and satanic worship. Garcia believes she has met her dream man, but her first date with him doesn't go exactly as she had expected.
As a team member fights for life, the BAU continues the search for an attacker that leads the unit to believe the assailant could be someone close to the investigation.
The BAU and local authorities in Los Angeles investigate gang-related serial killings that might possibly involve a famous comic book artist.
The new sheriff in Fredericksburg, Virginia, requests the BAU's assistance in the investigation of a series of mutilation murders that appear to mimic similar crimes that had occurred over two decades earlier.
When one teenager is found murdered and her best friend is abducted in Chula Vista, California, the BAU assists local authorities in determining whether the Witness Protection Program is involved.
After the contents of a self-storage unit purchased at an auction take the BAU to Philadelphia to investigate a series of murders, the local agent becomes the center of the case. To catch the killer, the team must profile the items inside the unit.
Rossi travels to Indianapolis to continue his investigation into the two unsolved murders that have plagued him for 20 years.
The BAU is called to Pittsburgh after an unusually high suicide rate appears to be the work of an Angel of Death.
The BAU is called to West Bune, a small town in Texas, to investigate what appears to be spree killings that involve a teenaged boy and his girlfriend.
The BAU is called to Miami to investigate a serial killer who appears to have a conflicted sexual identity.
The team members try to identify a stalker before he can attack a woman who is being stalked in Silver Spring, Maryland. Meanwhile, Hotch and Rossi are called as consultants on a possible battered woman syndrome murder case in Boston.
After a suspected serial killer wakes up from a coma, the BAU reopens the case and uses brain fingerprinting to determine if he really doesn't remember the crimes that had been committed four years earlier in Roanoke, Virginia.