FAIRPLAY, Colo. -- The man accused of strangling a University of Colorado-Denver graduate student appeared in court Monday where he was formally charged with first-degree murder.

The suspect, who has used the names Dennis Cook, Dennis Lee Cook and Robert R. Amos, is accused of killing a Colorado Geological Survey intern as she was conducting a geological study with her professor in a remote part of the San Isabel National Forest.

Escorted by six Park County deputies, a gaunt Amos walked into the courtroom on Monday shackled and looking disheveled in a red jail jumpsuit. He did not speak much during the proceeding, in which he was charged with 10 counts, including second-degree kidnapping and illegally possessing a weapon by a previous offender.

In court papers, Park County prosecutors classified him as a "habitual offender."

Amos' attorney noted that his client suffers from an illness and that he is taking medication for Parkinson's disease.

Amos was previously convicted of second-degree murder in the 1981 strangulation death of a 69-year-old music teacher in Kansas City. He served nearly 20 years in prison and was paroled in 2001.

Amos is now in jail on $800,000 bond.

When the judge referred to his several aliases and asked him what he would like to be called, Amos replied, "That's up to you, judge."

The judge said that he would call the suspect Dennis Cook.

But Amos replied, "No, go with Mr. Amos, please. Sorry." That elicited several chuckles from the courtroom.

Amos will next appear in court on July 23.

Alyssa Morimoto, 24, was found dead in the San Isabel National Forest west of Fairplay last Wednesday. An autopsy determined she had been strangled to death with a belt.

Morimoto and her instructor were mapping an area in the San Isabel National Forest Tuesday and had decided to separate earlier in the day so they could survey different areas. Morimoto took the Jeep and parked at the dead end of U.S. Forest Service Road 434, not far from Amos' campsite, authorities said.

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.

Morimoto's body was found about 10 hours later near Amos' campsite.

Morimoto was married six months ago. Her friends say she had a bright mind and vibrant curiosity about life. She was a graduate student in environmental sciences and was working on a mapping project when she was killed.

"She was just an amazing student. Always sharp and always curious. In college, she really took it to the next level with her studies," said Morimoto's best friend, Terrill Legeuri.