As part of the Boulder police's investigation, they accepted an invitation from the FBI to put on a full presentation of the case to the FBI's Child Abduction and Serial Killer Unit based at Quantico, Va. As Thomas recounts in his book, over 20 CASKU team members, including hair and fiber experts, attended the August 1997 briefing. Police investigators reviewed the autopsy results, and crime scene photos. In turn, CASKU agents reported that of the more than 1,700 murdered children they had studied since the 1960s, there was only one case in which the victim was a female under the age of 12, who had been murdered in her home by strangulation, with sexual assault and a ransom note present: JonBenet Ramsey. The agents told the Boulder investigators that while it might be possible that someone broke into the house that day, it was not very probable. The staging of the crime, the evidence presented to them by the Boulder police, and the totality of the case pointed in one direction: This was not the act of an intruder.
the FBI team said the crime "did not fit an act of sex or revenge or one in which money was the motivation. Taken alone, they said, each piece of evidence might be argued, but together, enough pebbles become a block of evidentiary granite."
"CASKU observed that they had never seen anything like the Ramsey ransom note. Kidnapping demands are usually terse, such as 'We have your kid. A million dollars. Will call you.' From a kidnapper's point of view, the fewer words, the less police have to go on."
The FBI "believed that the note was written in the house, after the murder, and indicated panic. Ransom notes are normally written prior to the crime, usually proofread, and not written by hand, in order to disguise the authorship."
the FBI deemed the entire crime "criminally unsophisticated," citing the child being left on the premises, the oddness of the $118,000 demand in relation to the multi-million dollar net worth of the Ramsey, and the concept of a ransom delivery where one would be "scanned for electronic devices." Kidnappers prefer isolated drops for the ransom delivery, not wanting to chance a face-to-face meeting.
CASKU profilers also observed that placing JonBenet's body in the basement indicated the involvement of a parent, rather than an intruder. A parent would not want to place the body outside in the frigid night. They also stated, according to Thomas, that the ligatures "indicated staging rather than control, and the garrote was used from behind so the killer could avoid eye contact, typical of someone who cares for the victim." Thomas said the profilers had the gut feeling that "no one intended to kill the child." This would mean that the severe blow to the head was done in a thoughtless rage and that all the subsequent assault on JonBenet and the writing of the ransom note was staged to cover up the unintentional murder.
Whoever killed JonBenet didn't fear getting caught. Thomas said that FBI profilers conjectured that the crime "was committed by someone who had a high degree of comfort inside the home. The murderer spent a good deal of time with the victim, bashing in her head, dragging her down two stories to the basement, wiping down her vaginal area, taping her mouth, tying up her wrists, garroting her, carefully, even lovingly, placing a white blanket over her, calmly writing what the Boulder police called the War And Peace of ransom notes, and then placing that ransom note just where Patsy Ramsey would be most likely to find it when she came down the backstairs in the morning.