A Prince George's County jury convicted early yesterday morning a 21-year-old man who had broken down in court Friday and confessed to shooting an off-duty Prince George's policeman who intervened during a February hold-up at Iverson Mall.

After almost 11 hours of deliberation the jury found Harlow Brian Sails guilty of first degree murder in the death of Raymond Hubbard. The conviction means that the jury believed the murder was premeditated and willful. The prosecution is seeking the death sentence. The jury also found Sails guilty of three counts of the use of a handgun in the commission of a felony and two counts of armed robbery.

On Friday, the fifth day of the Circuit Court trial, Sails had asked to take the stand and told the jury he had not been at Iverson Mall on Feb. 8 when his brother and three other men, later convicted, robbed Kay Jewelers. But under cross examination, Sails recanted the story, admitted he was lying and told the jury he shot Hubbard.

Sail's lawyer, Michael Gallavan, said yesterday that after the confession Sails was "relieved to have it off of his chest." When the verdict was returned at 4:30 a.m., Gallavan said Sails was tired, dazed and disappointed at the first degree conviction. But, said Galavan, "it's not like he thought it was impossible."

Circuit Court Judge Howard Chasanow has set the sentencing hearing for mid-February. Sails will be allowed to choose whether he wants his sentence decided by the jury or the judge. "From the beginning, we've been suggesting going with this jury," Gallavan said yesterday.

According to Maryland law, when the death penalty is sought, the prosecution must show "aggravating circumstances" in the killing to establish that the crime is particularly heinous. In this case, said Gallavan, those factors include that Sails killed a policeman, resisted arrest and committed murder during the commission of a felony.