Timothy Joseph Buzbee, identified by police as a prime suspect in what have become known as the Aspen Hill rapes, was found not guilty last night of a robbery charge in the first trial he has faced since being arrested last November.

Buzbee looked elated and then appeared to be fighting back tears as the foreman of the Montgomery County Circuit Court jury pronounced him "not guilty" of a 1980 street robbery in which a woman was attacked from behind and robbed of about $7.

The jury deliberated for less than three hours after a four-day trial in which the woman, Dorothy Barr, identified Buzbee as her attacker.

Buzbee will remain at the Montgomery County Detention Center where he has been incarcerated without bond since being arrested Nov. 5.

In the coming months Buzbee, a 25-year-old land surveyor who grew up in the county, will face charges involving five rapes. He has pleaded not guilty to all.

Late last night as the verdict was read, Buzbee's wife tightly gripped the hand of a friend and burst into tears at the foreman's words. William M. Buzbee Sr., the defendant's father, cried too and said as he left the court that the verdict in this first trial is "a step in the right direction.

"We feel all the charges are false and we can prove it with a reasonable jury, which this one was," he said.

The prosecution in the robbery trial contended that the woman's identification of Buzbee provided enough evidence to find him guilty.

The defense challenged the accuracy of the identification and said that the evidence "just is not adequate to convict anybody."

After 2 1/2 hours of deliberation, the jury took its only vote on the case--a unanimous vote for acquittal, according to jury foreman Yale Wiesberg.

The jurors felt that the prosecution's evidence, including the identification of Buzbee by the victim, was too weak and contradictory to sustain a verdict of guilty beyond a reasonable doubt, according to Wiesberg and juror Richard Lent.

Some of the jurors knew of the other charges Buzbee is facing, Wiesberg said.

But "never once" were those charges brought up during the deliberations, Lent said.

The closest anyone came to mentioning the other charges was when a juror questioned why the robbery case had been reopened and speculated that it might have to do with some other charge, Lent said.

But "everybody said we don't want to go into that," Lent added.

"It was a robbery charge at issue , and that's all we talked about."

The jury of six men and six women had been sequestered in a local hotel while not in the courtroom.

In his closing argument, defense attorney Reginald W. Bours III told the jurors that they were likely asking themselves, "What's the big deal? Why are we sequestered?" Bours added, "But we can't tell you."

Under Maryland law, the jury may not be told of any criminal charges against a defendant other than the one for which he is on trial.

The defense had requested the jury be sequestered because of the heavy publicity about the Aspen Hill rape cases.

According to testimony, Buzbee was stopped in the Woodmoor neighborhood a few blocks from the scene of the attack and robbery shortly after two citizens chased and lost the assailant.

Buzbee, in a short sleeve shirt on that December night, "trotted up to" one of the citizens and asked what was going on, according to the testimony.

The man detained him until police arrived with Barr.

Prosecutor Barry Hamilton argued that Barr identified Buzbee that night, although she noted that he was not wearing the army fatigue jacket and heavy gloves her attacker had worn. Hamilton told jurors that Buzbee "had an ample opportunity to conceal or discard" those items.

Defense attorney Bours attacked Barr's identification, saying that during the violent and brief struggle with her assailant, who attacked her from behind, "she just didn't look carefully at his face."

Bours argued that it was significant that police failed to arrest Buzbee that night.

"Do you think," Bours asked the jurors, "police would have let him go if Miss Barr had identified him as positively as she did on the witness stand?"