Criminal Minds is a police procedural that debuted on CBS on September 22, 2005. The series follows a team of profilers from the FBI's Behavioral Analysis Unit (BAU) based in Quantico, Virginia. The BAU is part of the FBI National Center for the Analysis of Violent Crime. The show differs from many procedural dramas by focusing on profiling the criminal, called the unsub or "unknown subject", rather than the crime itself. The series follows special agents Dr. Spencer Reid, Jennifer "JJ" Jareau, Penelope Garcia, Emily Prentiss, David Rossi, Dr. Tara Lewis, Luke Alvez, and Matt Simmons as they try to profile the unsub. Other former characters are Elle Greenaway, Jason Gideon, Jordan Todd, Ashley Seaver, Dr. Alex Blake, Kate Callahan, Derek Morgan, Aaron Hotchner and Stephen Walker.