The jury considering whether Harlow Brian Sails, convicted of the fatal shooting of a Prince George's County police officer, should be sentenced to die in Maryland's gas chamber was still attempting to reach a decision early today, almost two days after beginning deliberations.

The jury, which began deliberations at 9:20 a.m. Wednesday, continued without interruption until 4:30 yesterday morning before being sequestered in a motel. The jurors returned to the courthouse in Upper Marlboro to resume at 11:30 a.m. and were still deliberating as midnight passed.

Sails, a 21-year-old Riverdale man, was convicted in January of murdering the officer, Raymond Hubbard, 26, following the holdup of a Kay Jewelry Store at Iverson Mall on Feb. 8, 1982. Hubbard was off duty and out of uniform when he came upon Sails and four other men fleeing in a corridor and fired at them with his revolver. Sails shot the officer five times, according to testimony at his trial.

The Circuit Court jury considering Sails' fate heard two weeks of testimony plus closing arguments in which State's Attorney Arthur A. Marshall Jr. called the slaying a "cold-blooded execution" and defense attorney Michael Gallavan characterized it as the act of a desperate man in a situation that was "chaotic, panicky and fast."

Sails' mother, Mildred Mims, waited also, sometimes by herself and sometimes with relatives. Yesterday she waited by the courtroom door holding her son's 16-month-old daughter.

On Wednesday morning, Circuit Judge Howard S. Chasanow gave Sails consecutive prison sentences totaling 70 years for assault, robbery and gun offenses connected with the Iverson Mall holdup. He reminded Sails that the jury had been instructed that life in prison meant imprisonment for the rest of his natural life. "That's certainly what your crime calls for, and what I intend to insure" by making the related sentences consecutive, the judge told him. Under current parole system rules, Sails would be eligible for parole in about 27 years if he received a life sentence plus 70 years.