William Joseph Parker testified today that Prince George's County police questioned him for 7 1/2 hours before he finally became so "tired" and "rundown" that he incriminated himself in the murder of 13-year-old Elizabeth C. Archard.

"I had only had one hour of sleep and the medication (for a back operation) was affecting me," Parker said. He testified that police had alternately questioned him and left him alone for long periods in a windowless room. One officer followed him into the bathroom, he said, and two officers had failed to call a lawyer for him when he asked for one.

Parker's lawyer charged in opening statements that police had used "in effect, trickery" to get Parket to make a statement.

Asked in court today whether he believed the police had "tricked" him, Parker said "I'll take the Fifth Amendment on that one."

Parker, 28, is accused of picking up Archard about a mile from her Anapolis home last August 28, driving her to a wooded area outside Bowie, then raping her and shooting her five times.

If convicted of first degree murder and either rape or abduction, Parker could be the first person sentenced to death under Maryland's nine-month-old death penalty law.

Today, Parker, a volunteer fireman, took the stand in his own defense with the understanding that his testimony would be limited to the events of Sept. 14, the night he was questioned by Prince George's County police detectives and was eventually arrested.

Wearing a blue and red checked shirt, speaking in a clear voice which never wavered, Parker was led through his version of what happened that night by defense attorney Fred W. Bennett.

Parker testified that after arriving at police headquarters at about 5 p.m. he signed a waiver form, giving up his Constitutional right not to answer questions or have an attorney present.

That part of the story jibed with the testimony yesterday be detective Earl W. Jones, Tony R. Tucker and Wallis A. Sibila.

Jones, Tucker and Sibila testified earlier this week that Parker never asked for a lawyer, never asked to have his rights read to him a second time and never asked to leave the building during the seven hours prior to his arrest. Today, Parker denied those statements.

"After I made my written statement (early in the evening he wrote a statement denying involvement in the murder) Corporal Jones came back and asked me some more questions," Parker testified. "Then I asked him when I could leave because I had originally been told I was only going to be there for an hour. He said it would only be a couple more minutes."

Shortly after that, Parker said, he asked Jones if he could go to the bathroom and Jones escorted him there and followed him in even though he was not under arrest.

Parker also said he was left alone in interview room number 2 by Jones from 9:15 until 10:40 p.m. when Tucker came in to talk to him. Officer Jones had testified earlier that he was in the windowless, six by eight foot room during that time, accusing Parker of the murder.

"Jones came back after Cynthia (Parker's 17-year-old girlfriend Cynthia Bossert) told him I had been with her that day and said he (Jones) still thought I was involved," Parker said. "Then he left."

Parker said when Tucker came in, the two exchanged pleasantries, and then Tucker told him, "they've got the evidence on you and . . . Cpl. Earl Jones was going to charge me with first degree murder so it would be more better if I told him all about it.

"After that I told him I would like to have a lawyer present. He said he didn't know if he could get one at that time of night. I told him I knew Karl G. Feissner and asked him to contact him."

Moments later, Parker said, he asked Tucker to ask Sibila to come in and talk to him. "I knew Wally Sibila from when I was a fireman in Bowie," Parker said."I wanted someone who was going to be straight with me."

Parker said that Sibila came in at 11:25 p.m. and, after an exchange of greetings, told him he was going to be charged with the murder. "I said the same thing to him that I said to Tucker," Parker said. "I asked for a lawyer, I asked for Feissner.".

Parker, said that moments later he gave Sibila the oral statement in which he implicated himself in the murder. Bennett cut off his chronological questioning at that point because if he had questioned Parker about that statement Prosecutor Edmond B. O'Connell would have had the right to cross-examine him on its content.

Both attorneys rested their cases after Parker's testimony. Bennett then asked Chasanow, outside the jury's presence, to drop the first degree rape count. As Bennett recounted the details of Parker's written statement in which he said he had sex with Archard before "blacking out" to awaken and find her dead, Archard's parents, Philip D. Hale and Barbara Hale clutched one another. Mrs. Hale sobbed softly while her husband, who earlier had left the courtroom in tears, closed his eyes tightly.

The jury will receive instructions and hear closing arguments Friday morning and should begin deliberations by noon.