Not much is known about Benjamin. What is known is that he was born David James Merva and joined the Separatarian Sect previous to its destruction in 2008. Following this, he created his own cult called The Believers. He then became a serial killer, removing people's hyoid bones before strangling them in sacrificial killings.
Benjamin would kill young adults from all over the Continental United States. His victims were brought to him by Jerry Holston, a member of his cult. Benjamin would strangle his victims to death as his followers watched. His signature was torturing his victims by removing their hyoid bones, which were kept by in a suitcase, with seven being given to Jerry.
- Unspecified dates and locations from all over the Continental US: 299 unnamed victims (removed their hyoid bones before being killed)
- Spencer Reid (attempted to kill and remove hyoid bone; was rescued)
Victims by Proxy
- With his total body count of 299 people, Benjamin David Mervaa is the ninth of only nine unsubs in the show's history who are confirmed to have claimed the lives of hundreds. The others are:
- Season One
- Season Two
- Season Five
- Season Seven
- Season Ten
- Season Eleven
- Sharon Mayford ("Entropy") - A prolific and international serial bomber, hitwoman, cop killer, one-time mass murderer, and gangster who killed at least 173 people.
- Cat Adams ("Entropy", "Green Light", and "Red Light") - A prolific and international serial killer, hitwoman, gangster, and later proxy killer who killed over 200 people (an exact number unspecified). Adams also appears in Season Twelve.
- Season Thirteen