"We looked, we hunted, we spent months searching, but she is just gone and we don't know how," said Detective Lieutenant Terry Hopson, who has been on the case since Clea first went missing.
"We were told she walked out of that house at 8:30 p.m., but we have not been able to find a shred of physical evidence," he told Dateline.
However, investigators say they do have more than one person of interest.
"We can't rule anyone out," said Detective Lt. Hopson. "We can't even rule out that she left on her own
I don't know how you just disappear."
According to investigators, Clea's employer, Dr. Larry Amos, is considered a person of interest.
"In this case, the last person who saw her was Amos," said Detective Lieutenant Hopson. "But that doesn't make him guilty."
Laurell believes that Amos's behavior after Clea's disappearance seemed suspicious. "I don't think he has done enough to eliminate himself as a suspect," she said.