: Guest-starring as Spencer's father, William Reid.

: Reid suspects his estranged father, William Reid, may have been involved in the murder. This leads to a tense reunion between the two, as Spencer confronts the man who abandoned him and his mother years earlier.

How do you feel about the compared to more traditional procedural shows? "Criminal Minds" Memoriam (TV Episode 2008) - IMDb

: Spencer’s parents and the local sheriff had hidden the truth about Michaels' death for years to protect the family and the community, a secret that had contributed to the family's eventual collapse. Emotional Significance

is one of the most significant character-driven episodes in the Criminal Minds series, serving as the conclusion to the two-part storyline that began with "The Instincts." It focuses heavily on Dr. Spencer Reid as he attempts to reconcile fractured childhood memories with a cold case in his hometown of Las Vegas. The Investigation into the Past

: It is eventually revealed that Reid's father, William, did not kill Riley Jenkins. Instead, he confessed to killing Gary Michaels, a pedophile who had targeted Spencer after already murdering Riley.

The episode moves away from a traditional "unsub of the week" format to explore a deeply personal mystery:

: Spencer’s mother, Diana (played by Jane Lynch), is forced to confront her own suppressed memories. In a dramatic move, she goes off her medication to help Spencer uncover the truth about what happened the night Riley died. Key Reveals and Twists