Saying that policemen should be held to a higher standard, a Prince George's County Circuit Court judge yesterday sentenced a decorated D.C. officer to 10 years in prison for his role in an interstate car theft ring.

Judge David G. Ross imposed the prison sentence on Thurlow K. Norris, 42, despite warnings from his lawyer that his incarceration with criminals he may have arrested could amount to a "death sentence" for the 19-year member of the force.

Attorney Fred R. Joseph also urged that Norris, formerly of Greenbelt, be freed to support his wife, who is starting dialysis for kidney failure, and seven children in their care. Norris, who was formerly assigned to the 4th District in Northwest Washington, has been suspended without pay since his arrest in November 1986.

Ross also rejected judicial sentencing guidelines that call for probation to three months for the crime and the recommendations of the state Parole and Probation Department that Norris be placed in a work-release program.

Ross said Norris, who has no prior arrest record, deserved a "very high score" for a long list of commendations he received in his police work and citations given him during his military service in Vietnam.

But he cited the "misery suffered by so many victims in this offense."

"This was very deliberate on your part, occurred over a long period of time and was done with callousness towards the individuals who suffered losses," the judge said.

Norris, who supplemented his police salary by selling cars, has asserted he was set up by others and did not know the cars were stolen. "Had I had the foresight, I never would've entered into the automobile business," he said.

"I've lost 19 years of police work and my retirement" benefits, he said. "I have an unblemished record as a juvenile, adult and police officer. I fear for my safety {in prison}. I've made hundreds of arrests and convictions."

But Assistant State's Attorney Jeffrey L. Harding urged Ross to "send a message to the community that people in a position of trust should avoid even the appearance of impropriety." He recommended the 10-year prison sentence.

In a four-week trial in November, Norris was convicted on three counts of theft and one of conspiracy, and acquitted on seven other counts.

According to evidence, cars were stolen in New York and brought to Washington where they were sold after being given new serial numbers from salvaged automobiles.

One witness, Raphael Ortiz of New Jersey, testified that he drove cars from New York to the Washington area and that Norris had once referred to one of them -- a 1983 Toyota Celica -- as being "hot," or stolen.

Several of the jurors said they convicted Norris although they believed another witness when he recanted an earlier statement implicating Norris in the car theft ring. That witness, Joseph A. Young Jr., testified that his statements implicating Norris were made under coercion from another D.C. police detective.

Young identifed the detective as Curtis Arnold, a key figure in a federal probe into alleged leaks of information before a 1986 drug raid in the District.