At the scene of the kidnapping, police have also discovered signs of a struggle. Some of Cornwell's belongings turned up along Jones Creek Road, a rural road in north Georgia.
Richard Cornwell said his sister's boyfriend was not considered a suspect or a person of interest in the case.
But the people combing the countryside for Cornwell say they can't believe this is happening again. "We're in a rural community, you wouldn't think it would be like this," said one man who lives in the area.
Friends and family started a "Pray for Kristi Cody Cornwell" group on Facebook. There are more than 9,000 members so far.
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.
ABC News' Chris Strathmann, Joshua Gaynor and The Associated Press contributed to this report.