This undated family photo shows Alyssa Heberton-Morimoto, right, with her husband, Ryo Morimoto, on their wedding day. Alyssa, 24, was killed Wednesday while working with a geologic survey team in the San Isabel National Forest in Colorado.

Denver ? A man accused of killing a researcher in a remote Colorado forest and then giving a ride to her unsuspecting co-worker had been convicted of second-degree murder in Kansas 25 years earlier, state records show.

The suspect, who has used the names Dennis Cook, Dennis Lee Cook and Robert R. Amos, was being held Thursday for investigation of first-degree murder in the slaying of Alyssa Heberton-Morimoto, 24.

She was found dead late Tuesday in an isolated part of the San Isabel National Forest 75 miles southwest of Denver after pleading for help on a radio call.

Authorities have not said how she died. She had been on a mapping project.

Colorado officials said they weren’t sure which of the names used by the 44-year-old suspect is authentic. Kansas records show he was known as Dennis Cook when he was convicted of second-degree murder in 1982.

He was transferred to a Colorado prison later that year. Kansas officials would not disclose the reason but said it wasn’t overcrowding.

He was paroled in 2000.

Heberton-Morimoto was a summer intern for the Colorado Geologic Survey, which locates and maps such hazards as sinkholes and avalanches.

She was working on the mapping project with Karen Houck, a professor at the University of Colorado-Denver, where Heberton-Morimoto was a graduate student in environmental sciences, survey director Vince Matthews said.

Matthews said Heberton-Morimoto and Houck were working together on Tuesday but had separated to make their way to another site for lunch.

Houck heard Heberton-Morimoto’s cries over the radio but couldn’t find her. When Houck went for help, she unknowingly accepted a ride from the suspect, he said.

They encountered a forest ranger on the road, and Houck got into his vehicle.

“I think we’re extremely fortunate this isn’t a double tragedy,” Matthews said.

It wasn’t clear what the suspect did next. Park County sheriff’s investigators said he had been camping in the area, and they arrested him the day after Heberton-Morimoto’s body was found. They have not said what led them to the suspect.

No one answered Houck’s office or home phone Thursday.

Colorado Bureau of Investigation records show the suspect was arrested on suspicion of arson and attempted homicide in July 1993, but he was in prison at the time, and the state Department of Corrections has no record of those arrests.

CBI said someone else arrested on those charges may have used the suspect’s name or aliases.

The suspect is scheduled for another court appearance on July 2.