Prince George's County prosecutors dropped a felony perjury charge yesterday against a county police officer who had been accused of lying to protect a fellow officer. A judge had thrown out the key evidence in the perjury case.

A second judge then refused to postpone the officer's trial until after a new hearing on the crucial evidence.

The judges' decisions prompted harsh criticism from State's Attorney Jack B. Johnson, who said in an interview that he couldn't understand the judges' reasoning.

"We couldn't go forward [with the case] because of these strange rulings," Johnson said.

He said Circuit Court Judge Joseph S. Casula's decision to suppress statements the police officer made to a federal grand jury and FBI agents was "the strangest ruling I've seen in 24 years in the law."

Casula ruled on May 21 that Cpl. Rickey Rodriguez Davis's statements were the result of "sort of an ambush. It was a lot of psychological coercion."

Trial for Davis on the perjury charge was scheduled to begin yesterday before Judge E. Allen Shepherd, who denied a request by prosecutors to postpone the trial until after an Aug. 12 hearing before Casula. Prosecutors then dropped the charge.

"I don't understand these rulings at all," Johnson said. "I see why we have an 'enough is enough' movement in this country on [police misconduct] issues."

Casula was not in his office yesterday, a staff member said. Shepherd did not return a message left on a phone recorder at his office.

Davis, 36 and a nine-year member of the force, had been charged with lying in court about a 1994 incident in which Officer Timothy J. Moran beat a handcuffed Bowie man.

In November 1995, Davis testified in Circuit Court that Moran did not hit Peter Peluso, who was on trial for assaulting his neighbor and resisting arrest. Peluso was acquitted of both charges.

In May 1998, after an investigation by the FBI and the U.S. attorney's office, Moran pleaded guilty in U.S. District Court to violating Peluso's civil rights. Moran admitted in court that he had beaten Peluso with a police baton while Peluso was handcuffed.

During their investigation of the Moran case, FBI agents and the U.S. attorney's office in Maryland became suspicious of Davis's veracity, according to court records.

On Nov. 17, 1997, several months before Moran pleaded guilty, Davis met with two FBI special agents, an assistant U.S. attorney and a Justice Department lawyer to go over his testimony about the incident.

According to a transcript of a May 21 hearing before Casula, FBI Special Agent Margo Barber said Assistant U.S. Attorney Steven M. Dettelbach told Davis that a statement he had given was inconsistent with information they had received from other witnesses.

Davis stuck to his statement and took two polygraph tests, Barber testified. Both showed that he was being deceptive. Davis signed a "voluntary statement" that day and testified before the grand jury the following day, Barber testified.

Davis was indicted in February. His attorney, Robert C. Bonsib, challenged the admissibility of Davis's statements to the FBI, the U.S. attorney's office and the grand jury, arguing that Davis believed he was just a witness and that his statements were coerced.

Davis is restricted to administrative duties pending an internal affairs probe, police spokesman Royce D. Holloway said.