He didn't call 911 until many, many hours later. I think the Ramsey's were hoping somebody they'd invited into the house, even Linda Arndt would find JB before they did. Besides they were hoping that they'd staged it well-enough to convince people of the intruder theory, which apparently they succeeded at.
Also, the Ramsey's wouldn't take the police department's lie detector tests, only ones they privately selected months later, and even then it took Patsy 3 tries to pass!
One more thing to add: it's also been suggested by Patsy's mother that Patsy's father may have molested JB.
rockymtnnews:
Gelb's findings were reviewed and confirmed by Cleve Baxter, founder of the Central Intelligence Agency's polygraph unit and creator of polygraph scoring techniques considered industry standards.
The Ramseys were given what are known as single-issue examinations, where all questions in a test are designed to mean the same thing, Gelb said. Each test took two to three hours. The results cannot be skewed by drugs, so no screening was done, Gelb said.
The tests are 97-98 percent accurate, said Robert Lee, director of operations for Axciton Systems, which makes the computerized polygraph instrument used by Gelb.
The first test asked the following: Did you inflict any of the injuries that caused the death of JonBenet? Regarding JonBenet, did you inflict any of the injuries that caused her death? Were those injuries that resulted in JonBenet's death inflicted by you?
In the second test, Gelb asked: Do you know for sure who killed JonBenet? Regarding JonBenet, do you know for sure who killed her? Are you concealing the identity of the person who killed JonBenet?
Patsy Ramsey was given an additional test about the ransom note: Did you write the ransom note that was found in your house? Regarding the ransom note, did you write it? Is that your handwriting on the ransom note found in your house?
"Final conclusion: Based on extensive polygraph examination, neither John nor Patsy Ramsey were attempting deception when they gave the indicated answers to the relevant questions," Gelb said.
Baxter said his review confirmed Gelb's conclusion. "I could not fool the polygraph examination myself if a serious issue were involved. And I've been in the field a long time," he said.
..........the new DNA findings only confirm Gelb's findings, IMO.