"Magnum Opus" is the thirteenth episode of Season Eight of Criminal Minds.
While Reid copes with a loss in his personal life, the rest of the BAU travels to San Francisco to investigate a serial killer active in the Mission District.
- Jeff Adler - Man
- John Patrick Amedori - Bryan Hughes
- Alex Beach - Sherry Douglas
- Zach Book - Paul
- Ashleigh Borman - Aimee Fortner
- John R. Colley - Alan Archer
- Anna George - Doctor Barbara Moore
- Kate Hamilton - Kelly Miller
- Jamie Luner - Madison Riley
- Amy M. Morgan - Elaine Porter
- Brian Mulligan - Andre
- Melinda Stephan - Woman
- Craig Watkinson - Detective Lennon Miles
- Malachi Weir - Tre
- "Sugars of Someday" by American Head Charge
- "Just In Time" by Tony Bennett
- Jennifer Jareau: "My blood alone remains: take it, but do not make me suffer long." Marie Antoinette
- Spencer Reid: "Sometimes the hardest part isn't letting go but rather learning to start over." Nicole Sobon
- In Latin, magnum opus means "great work", referring to the largest, and perhaps the best, greatest, most popular, or most renowned achievement of a writer, artist, composer or craftsman.
- This is the first episode written by crew member and current script coordinator Jason Bernero.