Dear faces charges of murder in the first-degree. The next hearing to formally charge him was set for Dec. 9.
If convicted, he could face a minimum of life in prison to a maximum of the death penalty, court officials said.
Dear is being held in jail with no bond. For his court appearance via video he wore a padded jacket that jail officials called a "suicide prevention garment."
He was appointed public defender, Daniel King, who also represented Aurora movie theater shooter James Holmes.
While police haven't released a possible motive or said whether the clinic was the intended target, law enforcement sources told ABC News that Dear, 57, made rambling comments during the incident, some of which suggested animosity toward the health care provider.
Dear also allegedly made statements about President Obama during or after the incident that were concerning enough that he now has the attention of the U.S. Secret Service, which has dispatched agents to evaluate the remarks and possibly interview him, law enforcement sources told ABC News.
Police and federal agents Saturday used a bomb robot to search the mobile home and storage shed on the property in Hartsel, Colorado, where Dear lived. Hartsel is about 65 miles west of Colorado Springs.
Dear made an impression on Post the first time they met, he said, because he immediately gave him anti-Obama pamphlets.
"That was kind of weird that within three minutes of meeting somebody, they're already wanting to give you that kind of stuff," Post said.
"You could tell he wasn't that friendly of a guy," Gary Murr, another Hartsel resident, told ABC News. "He sure didn't smile or nothing. He would just answer a question and that's it."