While police initially considered the possibility that the abduction was connected to her former job as a parole officer, they are now leaning toward the likelihood that Cornwell, mother to a 15-year-old son, was kidnapped by a total stranger.
As police, state authorities and the FBI continue to comb the area and follow up on leads, Cornwell's family is trying to hold it together.
"We've still got that adrenaline pumping, and we're going to keep it going until we find her," brother Richard Cornwell told "Good Morning America" today.
Police do not yet have a suspect, and Cornwell's father, Harold Cornwell, said the kidnapper could be someone unknown to the family.
"I'd like to caution all young people and adults when using the Internet to meet people," he said.
Harold said that, since his daughter's disappearance, there are some nights when the family gets just one hour of sleep, but that they have vowed to keep up their end of the search while police continue the investigation.
"I want them to know what a wonderful woman Kristi was ... a woman of great faith," her mother, Jo Ann Cornwell, said. "And I just want them to keep looking for her."
Also keeping vigil is Cornwell's son, Brody.
"He's holding up, he's a strong boy," Jo Ann Cornwell said. "We just tell him how many people are looking for her, praying for her."
Earlier this week, the family released a home video in hopes the images will generate new leads.
On the video, Cornwell can be seen on the 1994 video bouncing her then infant son on her lap and opening Christmas gifts.
Richard Cornwell told ABC's Atlanta affiliate WSB that the family has set up a reward fund to encourage anyone with information to come forward.
"We're trying to get this reward fund built up," he said. "And we want this awful predator or predators put behind bars."
Mike Ayers, an agent with the Georgia Bureau of Investigation, told WSB that the FBI would bring in a behavioral scientist and assist with cell phone information.
Boyfriend Heard Kristi Cornwell's Abduction on the Phone
Cornwell was on her cell phone with boyfriend Douglas Davis as she was out for a stroll around 9 p.m. on Aug. 11.
Davis told police that Cornwell said a car was approaching her. He then heard a struggle and Cornwell yelled, "Don't take me".
Then Davis lost reception.
Jo Ann Cornwell said Davis's next call was to her to tell what he had heard. Horrified, she called 911.
"It terrified me," she said, her voice cracking. "I couldn't believe what he was saying."
"Her son needs his mother back, and I need my baby back," Jo Ann Cornwell said, crying. "And we believe we're going to get her back."
Richard Cornwell said that Davis, his sister's boyfriend, was not considered a suspect or a person of interest in the case.
Cornwell's cell phone was found Friday evening, according to police. A man found the phone while mowing his lawn more than three miles from where investigators believe Cornwell was kidnapped.
Richard Cornwell said that single piece of evidence has given the family the most hope that Cornwell would be brought home.
Found along a major thoroughfare, not the back street from where Cornwell disappeared, the phone indicates the kidnappers' route, Richard Cornwell said.
"That's very encouraging to me, because we know the direction of travel," he said. "We know they were heading north on state route 325."
From there, he said, they could have driven into Tennessee or North Carolina. Or, he said, just doubled back into Georgia.
"That gives me hope that there is still a good chance she's out there somewhere," he said.
Police, however, have told ABC News that they may soon be forced to scale back their search.
Police Believe Kristi Cornwell Is in Danger
At the scene of the kidnapping, police also discovered signs of a struggle and some of Cornwell's belongings along Jones Creek Road, a rural road in north Georgia.
The Georgia Bureau of Investigation believes Cornwell was abducted by a vehicle and is now searching for a white SUV and a tan or gold subcompact car, possibly a Toyota or Nissan, which were seen in the area on the evening of Aug. 11.
For nearly a week, 100 people from more than 15 agencies have been searching for Cornwell.
Last year, another woman, Meredith Emerson, disappeared in the same area of northern Georgia. She was found murdered, and her killer was caught and put behind bars.
But the people combing the countryside for Cornwell can't believe this is happening again.
"We're in a rural community, you wouldn't think it would be like this," one man who lives in the area said.
Friends and family started a "Pray for Kristi Cody Cornwell" group on Facebook. There are more than 3,000 members so far.
One message read, "We love you and Brody and are praying for your safe return."
Cornwell was very active in her community and her church, taking part in a mission to Jamaica with her son Brody.
Anyone with information can call the Union County Sheriff's office at (706) 439-6038, or the Georgia Bureau of Investigation at (800) 597-8477.
CLICK HERE for more information about Kristi Cornwell and the reward for information leading to her whereabouts.
The Associated Press contributed to this report.