What is the most disturbing thing someone has ever admitted to you?

as a case analyst at the prison, part of my job is to obtain the offenders crime version and enter it into the computer system. i had an offender tell me in detail how he kidnapped a 90 year old woman, raped her, put her in the trunk of her own car and drive around for hours before parking the car in the woods and then setting it on fire. he later found out the woman was the aunt of a state senator. he is serving a life sentence and his co-defendants received the death penalty.