Kevin Underwood, a 26-year-old grocery store stocker in a small community 40 miles south of Oklahoma City, is expected to appear in court for the first time since his arrest Friday.
Investigators searched his apartment after he aroused their suspicions at a checkpoint, and found a large plastic tub in a bedroom closet. According to a police affidavit, he confessed that he killed Jamie Rose Bolin, telling FBI agents: "Go ahead and arrest me. She is in there. I chopped her up."
Underwood also joked about cannibalism on his online diary, discussed the effects of not taking his anti-depression medication and mentioned "dangerously weird" fantasies.
All he wanted in life, Kevin Ray Underwood wrote in his blog, was "to be able to live like a normal person."
People who knew Underwood described him Sunday as a quiet, "boring" and seemingly trustworthy young man. His mother who lived across town called him a "wonderful boy."
"This is something that I don't know where it came from," Connie Underwood said of her son through tears in a brief telephone interview with The Associated Press. "I would like to be able to tell her family how sorry we are. I just feel so terrible."
Jamie's unclothed body was inside a tub in Underwood's apartment, along with a towel used to soak up blood, officials said. Police said that, while there were deep saw marks on the girl's neck, she had not been dismembered.
Underwood lived alone in an apartment downstairs from the one where Jamie lived with her father. Tim Bayer, the apartment complex's manager, is baffled since nothing in Underwood hinted at the face of evil, CBS News correspondent Mark Strassmann reports. "He was a quiet person," Bayer said.
Authorities believe Kevin Underwood killed the girl Wednesday, when she disappeared after going to a library, by beating and smothering her.
Investigators found meat tenderizer and barbecue skewers that he planned to use on the body, McClain County District Attorney Tim Kuykendall said.
On his blog, an online diary that he had kept since September 2002, Kevin Underwood described himself as "single, bored, and lonely, but other than that, pretty happy." His website also lists many of his personal hates, everything from the continuing focus on 9/11, all the way down to certain cartoon characters, Strassmann reports.
He mentions cannibalism, asking "If you were a cannibal, what would you wear to dinner?" and responding: "The skin of last night's main course."