State police investigated Lueth’s disappearance as a missing person’s case for months, but announced Wednesday they now are investigating it as a homicide.

But Krista Lueth’s father, Roy Lueth, said he has thought for a long time foul play was involved. Krista’s cat was left alone in the home, and she had a speech at MSU the next day.

“She wouldn’t just leave, because that’s not who she is,” Roy Lueth said.

Detective Sgt. Kevin Mark of the Michigan State Police said in December police would need some sort of evidence that Krista Lueth is dead to investigate the case as a homicide.

Although he said he could not comment on the reason for the change in the investigation or whether a suspect had been identified, Michigan State Police Detective Sgt. Frank Williams said investigators are doing everything they can to find Krista Lueth.

Roy Lueth said he just wants Krista back, even if it’s only to put her body to rest. Any information could help, he said.

“At least we’d know where she is,” the 67-year-old St. Clair man said. “She just doesn’t deserve to be just out there.”

In the time before her disappearance, Krista Lueth had just found out about an internship she couldn’t stop talking about. From where she sat near the front of horticulture professor Jesse Saylor’s classroom, Lueth always was engaged, taking notes and raising her hand.

Saylor said having Krysta Lueth remain missing has been hard on many horticulture students and staff members, many of whom knew her.

“There was so much hope that she would be found, but time goes by and it’s hard to keep that up,” he said.

Roy Lueth hopes finding the person responsible and putting them behind bars could prevent a similar incident.

“Maybe we can keep this from happening to someone else’s daughter,” he said. “Maybe we can save the life of someone who doesn’t even know their life has been saved.”

A reward of $15,000 is being offered for information regarding the disappearance. Anyone with information is asked to call CrimeStoppers at (517) 483-7867.