An Arlington judge ordered psychiatric tests yesterday for a Washington man accused of slaying a 22-year-old woman last month under what the prosecutor described as "extremely bizarre circumstances."

Commonwealth's Attorney Henry Hudson, who requested the examination, told Circuit Court Judge Charles S. Russell that the defendent, Skip Adams Taylor, has told police he had an "unusual motive" for the crime. Hudson did not elaborate.

Taylor, 20, a Northwest Washington man also known as George William Adams, is charged with murder in the death of Joyce D. Robertson, in her Arlington apartment on July 26. A medical examiner testified at a previous hearing that she had been strangled with the cord of her bathrobe and been struck with a small whip found near her body. Police also found the headless corpse of Robertson's pet parakeet at her side.

Hudson said two psychiatrists have concluded Taylor might have a "deep-seated emotional or psychiatric problem." The prosecutor said he wanted Taylor's fitness for trial to be evaluated now rather than just before the case is scheduled to go to court in late October.

After yesterday's court session, Taylor's lawyer, George D. Varoutsos, said, "Obviously there'll be some kind of insanity defense" to the murder charge. Taylor pleaded not guilty.

Varoutsos asked that the psychiatrist be barred from asking Taylor about Robertson's death, but Judge Russell rejected the request. The issue of whether the psychiatrist's statements should be admitted as evidence can be resolved later, the judge said.

Taylor is also charged with stealing stereo equipment and luggage from Robertson's apartment, a charge that will be considered during his trial on the murder charge.