In the end, it wasn't a fingerprint or a blood spatter that led authorities to the woman suspected of strangling a mother-to-be, cutting the baby from her womb, taking the baby home and passing her off as her own newborn.
The clue that cracked the case was an 11-digit computer code.
Police zeroed in on Lisa Montgomery in the most 21st century of ways, by trolling computer records, examining online message boards and - most important - tracing an IP address to a computer at her Melvern, Kansas, home. The Internet protocol address is the unique number given to every Internet-connected computer.
"That in and of itself led us to the home," FBI spokesman Jeff Lanza said.
Originally investigators believed Montgomery "stumbled onto" her victim on the Internet, reports CBS News Correspondent Cynthia Bowers, but a woman, who asked not to be identified, says Montgomery first spied Stinnett a year ago on the dog show circuit. Both bred rat terriers, and even appeared together in a group photo.
"Lisa always had to be the center of attention. She said she had a miscarriage and said she was pregnant again," the woman told CBS News.
Stinnett, 23, raised rat terrier dogs at home and had been expecting a potential customer the afternoon she was killed. In fact, she had to get off the phone with her mother because the customer was at the door, according to investigators.
Investigators say that just before the Dec. 16th slaying, Montgomery had corresponded over the Internet with the victim, Bobbie Jo Stinnett, about buying a dog from Stinnett. The same technology that makes instantaneous communication possible enabled authorities to crack the case in a matter of hours and rescue the premature baby.
Montgomery, 36, made a first appearance Monday before a packed courtroom in Kansas City, Kan. Montgomery is charged with kidnapping resulting in death. Wearing a navy-colored jumpsuit and slippers, she did not speak to the court as her public defender refused to waive her right to preliminary and identity hearings.
U.S. Magistrate Judge David Waxse scheduled both for 9 a.m. Thursday and declined a defense request for a gag order. Montgomery's public defender, Charles Dedmon, would not comment after the hearing.
Assistant U.S. Attorney Terra Morehead would not answer specific questions from reporters about the case, but authorities have said Montgomery - the mother of two children - has confessed to the crime. The 4-day-old girl, who was released from the hospital late Monday, is with her father, Zeb Stinnett, and is reported in "remarkably good" condition.
As that family faces the loss of Stinnett - whose funeral is Tuesday - the family of the accused killer and kidnapper is in another kind of shock.
"My heart ain't just broke for Lisa and them kids," said her husband, Kevin Montgomery, "for them too, that was a precious baby, I know."
Kevin Montgomery has not been charged; police say they don't think he knew his wife - who had claimed to be pregnant - was lying when she turned up with the hours-old baby and introduced the infant as their own.
Within hours of Stinnett's killing Thursday at her Skidmore, Mo., home, investigators realized the potential information her computer could hold in finding her killer.
In addition, investigators were racing against time to find the baby, who was one month premature when she was cut from her mother's belly and, it was feared, may have suffered oxygen loss or other trauma when her mother was strangled.
At the lab, clues seemed to pour out of the computer within minutes - who Stinnett had been e-mailing, what sites she had been visiting. Important tips from the public came in, too. Among them: a North Carolina dog breeder pointed to communications on a rat terrier message board.
"My adrenaline just started rushing," said the breeder, Dyanne Siktar. "I knew they could track the IP."
It turned out that at 4:22 p.m. on Wednesday, the day before Stinnett's slaying, someone identifying herself as Darlene Fischer posted a message to the victim on a rat terrier message board. "Please get in touch with me soon as we are considering the purchase of one of your puppies," it said.
About an hour later, Stinnett communicated with Fischer for about 20 minutes, investigators said. Then, at 7:44 p.m., Stinnett posted a message to Fischer: "I've e-mailed you with the directions so we can meet. I do so hope that the e-mail reaches you. Great chatting with you on messenger. And do look forward to chatting with you tomorrow a.m."
Investigators traced Fischer's IP address back to a dial-up connection from the Melvern home of Montgomery and her husband.
On Friday, less than 24 hours after the slaying, investigators pulled up to the couple's home in Kansas, found the baby and arrested Montgomery.
As for how the killer knew Stinnett was about to become a mother, Stinnett had a Web site about her dogs that investigators said may have included a picture of Stinnett pregnant. The FBI would not comment on whether the pair had ever met before last week, or how the killer knew Stinnett was still pregnant.