A source close to the investigation told CBS News the reason investigators moved in on Karr was because of details in these emails about the Ramsey house that had not been made public, reports CBS News correspondent Kelly Cobiella.
According to the source, Karr wrote about a check stub on John Ramsey's desk in the amount of $118,000, specifics about a staircase in the Ramsey's home and details about the basement where JonBenet was killed.
The e-mails were suspicious for other reasons as well. Correspondence obtained by the Rocky Mountain News included one message in which the professor was asked to visit JonBenet's home in Boulder to read aloud an ode called "JonBenet, My Love."
"JonBenet, my love, my life. I love you and shall forever love you. I pray that you can hear my voice calling out to you from my darkness, this darkness that now separates us," read one of the e-mails, which the newspaper said Friday it obtained from a source close to the investigation.
In other e-mails, Karr said he was under federal investigation for "child murder and child molestation" in four states.
"I don't know that he's guilty," said Tracey. "Obviously, I went to the district attorney for a reason, but let him have his day in court and let JonBenet have her day in court and let's see how it plays out."
In another e-mail, the Rocky Mountain News reported, Karr said he sympathized with Michael Jackson, who was accused but later acquitted of molesting young boys.
"I will tell you that I can understand people like Michael Jackson and feel sympathy when he suffers as he has," Karr wrote.
"I can relate very well to children and the way they think and feel," one Karr e-mail said. "I think you are asking if I am much a 'Peter Pan.' In many ways, the answer is yes. In other ways, I suppose it is no, because I am trapped in a world that does not understand."
In another correspondence, Tracey asked whether Karr's "fascination with little girls, which clearly has a strong erotic component, is a way of going back."
"Maybe I am not going back but have simply stayed consistent," Karr responded. "My peer group has not changed since I was a little boy, and girls were the people I was with always. Referring to them as a peer group is somewhat incorrect, but might also be the very definition of what they continue to be in my life."
Meanwhile, in California, prison guards searched the death row cell of a child killer after learning he may have corresponded with Karr, authorities said Friday.
Guards at San Quentin State Prison searched Richard Allen Davis' cell Thursday, but no letters were found from Karr, said Lt. Eric Messick.
In Washington, federal law enforcement officials said Karr's comments since his arrest have piqued their interest and they want to question him. Regarding Kerr's purported claims in e-mails that he was under federal investigation for child murder and molestation, one law enforcement official said "there is no four-state federal case" in which Karr is wanted or even suspected.
Meanwhile, investigators continue to unravel an elaborate and hazy narrative woven in part by Karr himself, much of it constructed around a clear and chilling theme — a yearning to be close to children.
That desire, in retrospect, appears as heartfelt as it does disturbing.
In an interview for an English-teaching job at one of Bangkok's elite Thai schools, Karr left a good first impression. He was clean-cut, articulate and had a resume detailing experience in schools in the United States, Japan and elsewhere.
But after just two weeks on the job, Karr was asked to leave.
"John Karr came to us with a good resume and with credentials, but then we allowed him a trial (period) with students, we found he was too strict," Banchong Chompowong, assistant director of Bangkok Christian College's English immersion program, told The Associated Press on Friday.
Karr is a man who, while wanted as a fugitive on child pornography charges, sought to impress prospective employers with a long record of accomplishment preparing young lives "for a successful future."
Karr went through his teen years mostly unnoticed, one of his classmates told CBS News 48 Hours correspondent Erin Moriarty, keeping mostly to himself.
He is a man who twice married teenagers — one just 13 at the time. Both would later claim they had been coerced.
And he is the man who years ago confided to family members that he was deeply troubled by the murder of the Colorado 6-year-old, who told U.S. investigators that he picked JonBenet up at school, drugged and had sex with her before in Colorado in 1996, Thai police Lt. Gen. Suwat Tumrongsiskul told The Associated Press.
But questions have been raised about some of his claims, including whether he drugged the 6-year-old, sexually assaulted her or was even in Colorado at the time of the slaying.