COLORADO SPRINGS, Colo. -- A man who acknowledges killing three people in an attack on a Colorado Planned Parenthood clinic defiantly told a judge Wednesday that he would not submit to a mental competency evaluation and wanted to fire his public defender and represent himself.

Robert Dear, 57, interrupted Judge Gilbert A. Martinez during a hearing where Martinez went ahead and ordered the evaluation to determine whether Dear is capable of deciding to represent himself.

Martinez told Dear it was his right to refuse to answer an evaluator's questions. Dear replied that if he did not co-operate, a doctor would declare him incompetent and "administer the drug treatment and make me a zombie."

"Do I sound like a zombie? Do I sound like I have no intelligence?" he asked the judge.

Dear, unkempt and wearing blue jail scrubs, repeatedly interrupted the status hearing held to discuss a range of issues related to the Nov. 27 shooting at the Colorado Springs clinic.

Martinez at one point warned Dear that whatever he said could be used against him and advised him to trust his lawyers.

"How can I trust my attorney when he says I'm incompetent in the newspaper?" Dear replied.

Martinez then cleared the courtroom of spectators to privately discuss the possibility of Dear defending himself.

When the courtroom re-opened, Deputy District Attorney Donna Billek objected to the competency evaluation, saying Dear had repeatedly made it clear through his statements in court that he understood the proceedings and the charges against him.

Martinez ordered the exam to take place at a state mental hospital, where a backlog of orders for such evaluations made it unclear when it could be completed.

Attorneys who are not involved in Dear's case say it isn't unheard of for defendants to refuse to participate in a competency evaluation, but they can be forced to attend even if they don't answer questions.

During the hearing, Dear repeatedly referred to the unresponsive courtroom behaviour of Colorado theatre shooter James Holmes, who was medicated during his four-month trial.

After Dear made his comment about being turned into a zombie by a doctor, he mimicked Holmes by slumping in his chair and referring to the "Batman guy." Holmes was convicted of opening fire at the premiere of a Batman movie.

Prosecutors have yet to decide whether to seek the death penalty against Dear. Much of his legal team -- from lead attorney Daniel King, a public defender, to his paralegals -- also represented Holmes.

Dear faces 179 counts, including first-degree murder, attempted murder and other charges. At a court appearance earlier this month, he declared himself guilty, said he is "a warrior for the babies" and objected to the sealing evidence in his case.

On Wednesday, he claimed he was being poisoned in jail and urged the judge to have a sample of his hair tested to "see if there's any drugs that have been put into my system while I've been in jail."

Dear's family and acquaintances describe him as a man with a violent temper, anti-government sentiments and longstanding disgust toward people who provide abortion services. He spent most of his life in North and South Carolina before recently moving to an isolated community in Colorado's mountains, where he lived in a trailer with no electricity.

Authorities have revealed little about the preparations behind the attack, where Dear held police at bay for more than five hours. Nine other people were injured in the attack that forced the evacuation of 300 people from businesses surrounding the clinic.

Dear's next court appearance is Feb. 24.