Richard Poplawski walked into the small courtroom quickly and quietly yesterday, a sheriff's deputy holding his arm.

A scraggly beard and red pimples covered his boyish face. His thick brown hair was slicked back. He wore a red prison jumpsuit, and his hands and legs were shackled.

As he stood before District Judge Kevin E. Cooper in the Municipal Courts Building, Downtown, Mr. Poplawski showed no emotion.

"I need you to make sure you understand you're waiving your right to a preliminary hearing," Judge Cooper told the 22-year-old man, who is accused of shooting and killing three Pittsburgh police officers.

"Do you understand the severity of those charges?"

"Yes, sir," Mr. Poplawski replied.

It was his first appearance in public since April 4, the day of a lengthy shootout with police in Stanton Heights and the deaths of Officers Paul J. Sciullo II, Stephen J. Mayhle and Eric G. Kelly.

Police said Mr. Poplawski was armed with an AK-47 style assault rifle and was wearing a bullet-proof vest during the confrontation. He was shot in the legs, but the vest absorbed a gunshot to the chest.

Yesterday, he seemed to have fully recovered from his injuries. He walked without any noticeable limp.

Mr. Poplawski had been scheduled to go before a judge tomorrow morning. But Lisa G. Middleman, his court-appointed attorney, persuaded him to bypass the preliminary hearing, where prosecutors would have presented witnesses and would have tried to show they have enough evidence for a full trial by jury.

It also likely would have included an overwhelming media presence and heavy security. Officials had planned to move the hearing to a larger courtroom in the Allegheny County Courthouse on Grant Street.

"I think it was best for him," Ms. Middleman told reporters. "It was the best thing for everyone involved."

Still, Mr. Poplawski was required to appear in court yesterday to sign the hearing waiver. The process took five minutes.

Judge Cooper called the case "extremely serious," and he reminded Mr. Poplawski of his rights.

"This doesn't mean you are guilty of the charges," the judge said. "Do you understand that?"

With a small group of reporters and police officers watching from behind a metal fence, Judge Cooper read each of the 28 criminal charges Mr. Poplawski faces: three counts of homicide, nine counts of attempted homicide, two counts of discharging a firearm into an occupied structure, four counts of reckless endangerment, and one count of possessing "unlawful body armor."

Deputy District Attorney Mark Tranquilli asked the judge to amend nine additional assault charges to be "assault on a law enforcement officer," which carries a stiffer penalty.

Ms. Middleman did not object to the changes, and Judge Cooper then read the names of nine officers who came under fire April 4, including Officer Timothy McManaway, who was hit in the hand while trying to rescue Officer Kelly.

Again, the judge asked Mr. Poplawski whether he understood the "severity" of the accusations.

Again, Mr. Poplawski said in firm voice: "Yes, sir."

As his lawyer looked over his shoulder, Mr. Poplawski then signed the waiver.

Judge Cooper set June 1 as the date for a formal arraignment. A sheriff's deputy guided Mr. Poplawski out of the courtroom. He is being held without bond in the Allegheny County Jail.

Before the arraignment date, the office of Allegheny County District Attorney Stephen A. Zappala Jr. must announce whether prosecutors plan to seek the death penalty against Mr. Poplawski.

"We do not yet have all the information necessary to decide how we are going to proceed on this case," Mike Manko, a spokesman for Mr. Zappala, said yesterday.

The district attorney's office is still researching Mr. Poplawski's background, "including educational, medical and military records," Mr. Manko said.