FAIRPLAY, Colo. -- The camper accused of killing a 24-year-old Colorado Geological Survey intern had served 19 years in prison for murder, according to state records.

A U. S. Forest Service Park Ranger met that camper, before he was arrested again.

Robert Amos, who is also known as Dennis Cook or Dennis Lee Cook, is being held on $800,000 bond. He faces first-degree murder charges.

Alyssa Heberton-Morimoto's body was found Tuesday night, lying in a shallow creek in a remote part of Park County, close to Amos' campsite. She had a gray and green strap wrapped around her neck, according to the arrest affidavit.

Her body had been partially covered with tree branches and nearby, deputies found a rifle and a shoe impression.

Her cause of death has not been officially released.

Heberton-Morimoto went to the San Isabel National Forest with her geology professor earlier in the day. The two women separated so they could survey different areas. Heberton-Morimoto took the vehicle and parked at the dead end of U.S. Forest Service Road 434, not far from Amos' campsite, authorities said.

Heberton-Morimoto radioed her instructor, Karen Houck, that she spoke with "some camper" and received permission to park the vehicle near his campsite, Houck said. About 20 minutes later, she screamed, "Karen, help! Help! Help!" There was another radio transmission with just her screaming for her life, Houck told officers.

Houck, an instructor at the University of Colorado at Denver, used the coordinates on the GPS radio to run toward her.

When she reached that area, she saw that the Jeep was parked, the back hatch was open, but all of Heberton-Morimoto's gear was in the Jeep. The vehicle key and Heberton-Morimoto's radio was missing, Houck said.

Houck looked around, walked to the campsite, about 25-30 yards away, but no one was there. She said she walked about a quarter-mile on the U.S. Forest Service Road and that's when she spotted Amos jogging towards her.

She said Amos slowed down and came walking up the road. She asked him if he had seen Heberton-Morimoto. He told her that he didn't know where she was and had "seemed confused," according to the arrest affidavit.

She told him what had happened, that she needed to get in cell phone range to call the sheriff's office and then asked him for a ride. She told others she never felt threatened in his presence. As they drove toward the highway, they encountered a forest ranger so Houck got out of the vehicle.

That forest ranger told deputies that when she saw Houck and Amos, he was wearing wet shoes and his jeans were wet 2 to 3 inches above the hem.

Amos was taken in for questioning and was later arrested in connection with Heberton-Morimoto's death.

That Ranger is a District Ranger who tells 7NEWS she's never sen anything like this in her 17 years patrolling and managing Colorado's forests.

"It's a little disconcerting because it means the safety for me and my employees maybe isn't what I thought it was," the Ranger said

She is concerned..."that this could happen to somebody just doing their job."

Deputies who had been sent out to search for Heberton-Morimoto found drag marks from Amos' campsite leading to the gray Jeep, then toward the creek, according to the affidavit.

Amos had been camping in the area by himself. Authorities said he's from out of state and has a lengthy criminal record. During questioning, Amos showed detectives two different types of pills from his pocket. He said that he was taking the pills for stage-three cancer.

He said that he had left his campsite Tuesday morning at about 9 a.m. or 9:30 a.m. and did not return until he saw Houck. This contradicts Houck's statement that Heberton-Morimoto had called to say that she had spoke to "some camper" before she parked the Jeep next to his campsite.

Amos, 44, was convicted in a 1981 murder in Kansas. He was sentenced in 1982 to 15 years to life in prison.

He served a total of 19 years in Colorado and was also convicted of assault while in prison, according to Department of Corrections spokeswoman Katherine Sanguinetti. After he was released in 2001 for parole, he served probation in Kansas for another two years.

In 2003, he was officially released from Colorado's correctional system having served at four facilities in Buena Vista, Centennial, Colorado State Penitentiary, and San Carlos State Penitentiary in Pueblo.

It is unclear if he was stalking Heberton-Morimoto or if the killing was random, officials said.

"We are confident that there were no other individuals involved in this case," Park County officials said.

Amos' vehicle is registered in Kansas. He told authorities that he had been at the camping site for the past two or three days.

Deputies also found a Japanese Samurai-style sword, axes and a machete at his camp site. A wet pair of jeans hanging from a tree and a wet pair of black tennis shoes on the ground in front of his pickup truck were also noted in the affidavit.

Deputies spoke to campers about 1.5 miles away. They told detectives that they saw a man in the area of Forest Service Road 434 between 10:30 a.m. and 12 p.m. and that they heard noises similar to a gunshot or firecrackers sometime in the morning.

Heberton-Morimoto was a student at the University of Colorado Denver's campus and was working on a master's degree in environmental science. She started working on a Colorado Geological Survey mapping project on June 1 for the summer with Houck. She was mapping geological hazards, including mudslides, faults and sinkholes from underground dissolving salts.

Her friends and professors said her death is a senseless waste of a great talent and an amazing person.

"I think she just found beauty in people reaching out and helping each other," said Heberton-Morimoto's best friend, Terrill Legeuri.

Her friends and family take some comfort knowing that she was very happy in her life. She was married six months ago and was pursuing her dream.

"She always felt very blessed that she had opportunities to do research, especially with Karen, her professor," Legeuri said.

This was her second summer working with Houck, who recommended her for the job. Houck had taught Morimoto's first geology class, officials said.

Before pursuing her graduate degree, Heberton-Morimoto received her undergraduate degree from CU Denver and graduated with distinction. She was a high school graduate from the Denver Waldorf School and had been an exchange student in Germany.

What's ironic, friends say, is that Heberton-Morimoto battled fear every time she went camping or hiking. She was afraid of bears and lightning, but she fought it, friends said.

"She was really into that. She says, 'You can't live a life of fear.' I mean, there's no one like her. I will never be able to replace the scope of interest and imagination and her ability to listen and respond," Legeuri said.

Both the Park County Sheriff's Office and the Colorado Bureau of Investigation are investigating the case. Anyone with information about the case is asked to call the Park County Sheriff's Office at 719-836-2494.