A judge ruled Wednesday that John Allen Muhammad can represent himself at his trial for six killings during the 2002 Washington-area sniper attacks.

Circuit Judge James L. Ryan concluded that Muhammad is competent to represent himself despite evidence presented by his own attorneys that Muhammad might be mentally ill.

Muhammad is already under a death sentence for a sniper attack committed in Virginia.

Muhammad, 45, and Lee Boyd Malvo, 21, are accused of murdering 10 people and wounding three during the three-week rampage in October 2002 that spread fear across the Washington metropolitan area.

Muhammad's trial in the six Montgomery County, Md., slayings is set for May 1. Malvo, who was also convicted in Virginia and sentenced to life in prison, is scheduled to go on trial in the fall.

Muhammad vehemently denied a psychiatrist's report, presented by his lawyers, stating that he is paranoid, delusional and had a form of schizophrenia.

"There is no reason at all why I should not be able to represent myself in this trial," he said. "If I had a mental disorder, then Rosa Parks had a mental disorder, because she didn't get up off that seat."

Muhammad stood throughout the two-hour hearing and spoke frequently, often sparring with his attorneys. At one point, he asked the judge for permission to sit with the prosecutors because they agreed that he is competent. Ryan ignored his request.

In agreeing that Muhammad could act as his own attorney, Ryan stressed that Muhammad was making a bad decision because he has no legal training and little legal experience.

Muhammad's attorneys said afterward that the judge had refused to hold a full hearing with witnesses.

"We feel we didn't get a chance to present and document evidence of a serious mental illness," said defense attorney Paul DeWolfe. "He is very ill; he is mentally ill."

The judge appointed DeWolfe and another lawyer as standby attorneys, giving them an advisory role so the defendant can ask them law questions and get help with legal filings.

Muhammad briefly represented himself during his trial in Virginia, delivering an opening statement and cross-examining at least one witness. He eventually allowed his attorneys to retake control of the case.