Karl Arnold

Karl Arnold, Jr. was a psychiatrist whom the BAU investigated in season one of Criminal Minds.

Background
Karl worked at the clinic where all the victims had been having therapy. He was driven to kill by the fact that his wife had taken his children and left him. He felt that he had been a failure as a husband and a father and so spent a while pretending to be the father figure before killing the entire family starting with the youngest first.

Profile
Karl was highly organised and made the killings look like murder-suicides. The team was lead to him due to the fact that both families worked for the government so they had the same HMO and the same therapist clinic. They originally suspected their prescribing doctor, Dr Rachel Howard, as she also fit the description offered by Mrs Crawford's brother. He killed the Miller family and the Crawford family and took the husbands wedding rings as trophies. In his office, Hotch found a box with several more wedding rings inside.

Modus Operandi
Karl would live with his victims for awhile, posing as a father figure to not only get closer to them, but build his self-assurance. He would then kill them, effectively exerting total control over their lives.

Appearances

 * Season One
 * The Fox