| 66 (4-01) | "Mayhem (2)" | September 24, 2008 | 401 |
| After a bomb explodes an SUV in New York City that might be carrying a BAU member, the team goes into high gear to determine who might have been injured in the explosion and to apprehend the terrorists responsible for the mayhem. | |||
| 67 (4-02) | "The Angel Maker" | October 1, 2008 | 402 |
| After a series of murders in Lower Canaan, Ohio, is connected to a serial killer who had been executed a year ago, the BAU must find the link to the current crimes. | |||
| 68 (4-03) | "Minimal Loss" | October 8, 2008 | 403 |
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After Prentiss and Reid go undercover in Colorado to investigate alleged child abuse at the compound of an underground cult in La Plata County, they are taken hostage when a federal raid on the fortress goes bad. Special Guest Star: Luke Perry |
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| 69 (4-04) | "Paradise" | October 22, 2008 | 404 |
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The BAU joins the manhunt in Sherwood, Nevada, to catch a serial killer who conceals the manner of his crimes by staging car accidents. Special Guest Star: Wil Wheaton |
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| 70 (4-05) | "Catching Out" | October 29, 2008 | 405 |
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The BAU investigates a series of murders in California's Central Valley that appear to be connected to a killer who jumps trains and chooses his victims based on their proximity to the railway. Special Guest Star: Andre Royo |
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| 71 (4-06) | "The Instincts (1)" | November 5, 2008 | 406 |
| When a young boy is kidnapped in Las Vegas, Reid begins to have dreams that force him recall forgotten memories from his childhood as he investigates the case. | |||
| 72 (4-07) | "Memoriam (2)" | November 12, 2008 | 407 |
| As Reid's investigation of a young boy's murder in Las Vegas continues, he discovers possible connections to his own past. | |||
| 73 (4-08) | "Masterpiece" | November 19, 2008 | 408 |
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When a narcissistic psychopath confesses he has killed seven people and more will die, the team must locate his latest victims before it is too late. Special Guest Star: Jason Alexander |
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| 74 (4-09) | "52 Pickup" | November 26, 2008 | 409 |
| Emily Prentiss and Jordan Todd go undercover in Atlanta to profile a serial killer who has perfected his skill as a pick-up artist and uses his masculine prowess to lure his next victims. | |||
| 75 (4-10) | "Brothers in Arms" | December 10, 2008 | 410 |
| As a former uniform cop, Morgan takes it personally when a serial killer specifically targets officers on the police force in Phoenix, Arizona. | |||
| 76 (4-11) | "Normal" | December 17, 2008 | 411 |
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The BAU is called to assist local law enforcement in catching a serial killer, dubbed the "Road Warrior" by the media, who is shooting blonde women as they drive along freeways in Orange County, California. The case is complicated because the heinous acts appear to be at random and the shooter is described as looking normal. Meanwhile, JJ brings her new baby to the BAU headquarters to introduce him to the team. Special Guest Star: Mitch Pileggi |
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| 77 (4-12) | "Soul Mates" | January 14, 2009 | 412 |
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When a young woman in an affluent community in Sarasota, Florida, disappears, the BAU suspects she may have been taken hostage by the partner of a pair of serial killers. Special Guest Star: Michael Boatman |
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| 78 (4-13) | "Bloodline" | January 21, 2009 | 413 |
| The BAU is called to Alabama when young girls are abducted by what appears to be a family working together. | |||
| 79 (4-14) | "Cold Comfort" | February 11, 2009 | 414 |
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The mother of an abducted child works with the BAU in Seattle to identify a serial killer who kidnaps, murders, and embalms his victims. Special Guest Star: Cybill Shepherd |
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| 80 (4-15) | "Zoe's Reprise" | February 18, 2009 | 415 |
| The local authorities in Cleveland enlist the help of the BAU to assist in the pursuit of a serial killer who appears to be copying the methods used by famous murderers from the past. | |||
| 81 (4-16) | "Pleasure is My Business" | February 25, 2009 | 416 |
| The BAU is called to Dallas to investigate when a serial killer lures and kills high-powered executives by posing as a high-class call girl. | |||
| 82 (4-17) | "Demonology" | March 11, 2009 | 417 |
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The BAU investigates a series of deaths involving possible exorcisms in the Washington area that appear to be sanctioned by the Vatican, and SSA Emily Prentiss finds herself personally involved in the case. Special Guest Star: James Remar |
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| 83 (4-18) | "Omnivore" | March 18, 2009 | 418 |
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The BAU travels to Boston when the serial killer from one of Agent Hotchner's first cases, which involved one of the most notorious murderers in the history of New England, returns after 10 years. Special Guest Star: C. Thomas Howell |
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| 84 (4-19) | "House on Fire" | March 25, 2009 | 419 |
| The BAU is summoned to Indiana by local authorities when a serial arsonist threatens the residents of Royal by setting fire to community meeting places that kills many people. | |||
| 85 (4-20) | "Conflicted" | April 8, 2009 | 420 |
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The BAU is called to Texas to investigate a serial killer who is targeting vacationing students on spring break on South Padre Island. Special Guest Star: Jackson Rathbone |
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| 86 (4-21) | "A Shade of Gray" | April 22, 2009 | 421 |
| During an investigation of a series of child abductions and murders in Cherry Hill, New Jersey, the BAU concludes the possibility that the last murder may not be the work of the suspect who had been apprehended. | |||
| 87 (4-22) | "The Big Wheel" | April 29, 2009 | 422 |
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When a serial killer in Buffalo sends a videotape of one of his crimes to the BAU, the team discovers a message from the murderer that begs for help in stopping the killing. Special Guest Star: Alex O'Loughlin |
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| 88 (4-23) | "Roadkill" | May 6, 2009 | 423 |
| Local authorities summon the assistance of the BAU after a series of homicides occur that appear to have been caused by a serial killer's car near Bend, Oregon. | |||
| 89 (4-24) | "Amplification" | May 13, 2009 | 424 |
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The BAU responds quickly after a serial killer releases a new strain of a deadly anthrax virus in Annapolis that threatens the public and puts a member of the team at risk. Special Guest Star: Dan Lauria |
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| 90 (4-25) | "To Hell... (1)" | May 20, 2009 | 425 |
| In one of its most difficult cases, the BAU is called to Detroit to help track down a serial killer who forces the team into Canada to catch him. | |||
| 91 (4-26) | "...And Back (2)" | May 20, 2009 | 426 |
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The BAU continues its search for a serial killer who has forced the team into Canada to catch him. Meanwhile, a team member may have become the target of a killer from the past. Special Guest Star: C. Thomas Howell Note: Pt. 1 & Pt. 2 are based on the Robert Pickton murders that took place in Vancouver, BC and certain elements also resemble the plot and characters of the Thomas Harris novel Hannibal |
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As Rossi, Morgan and JJ profile a killer who is targeting an emergency room doctor, Prentiss realizes that Hotch