A judge has dropped first degree murder charges against two men indicted in the 1977 slaying of an Arlington police officer after the county prospecutor said there was serious doubt about the guilt of one defendant and insufficient evidence to prosecute the other.

A third man is still charged in the fatal shooting of Officer John W. Buckley, but the prosecutor, Henry E. Hudson, said yesterday he will recommend dropping that first degree murder charge too.

Circuit Court Judge William L. Winston dismissed the charges against Theodore Lawler and Donald Eugene Anderson on Monday after Hudson said a two-month investigation raised "serious doubt of the guilt" of Lawlor and there wasn't enough evidence to prosecute Anderson.

When a county grand jury indicted the two men along with Jose Otero last year, then prosecutor William S. Burroughs said Anderson and Lawler shot Buckley to death during the robbery of a South Arlington bank in April 1977. Burroughs said Otero allegedly drove a getaway car.

In a prepared statement, Hudson said that in the next week he will recommend dropping the charge against Otero because there is serious doubt about his involvement in the crime.

Attorneys for all three men have said none was in Arlington at the time of Buckley's murder.

Hudson, who took office as prosecutor in January, said his decision to drop prosecution was made after consultation with Police Chief William K. (Smokey) Stover and was based on a two-month investigation by an Arlington detective and an assistant prosecutor.

Last November Circuit Court Judge Charles H. Duff declared a mistrial during Anderson's trial after the chief prosecution witness, 19-year-old Donald Garrison, failed to appear in court.

Garrison, who had previously served a one-year sentence for driving one of the getaway cars following the robbery, was sentenced to last week to serve five months in a jail for contempt of court.

Authorities said Anderson and Lawler, who are serving prison sentences for other crimes in Leavenworth Penitentiary and a Florida prison, respectively, will be returned to those facilities soon.