A jury was seated Monday in a trial to decide who is the rightful owner of a .38-caliber Colt Cobra revolver Jack Ruby used to kill presidential assassin Lee Harvey Oswald. The case before Dallas County Probate Judge Robert E. Price could end 23 years of legal wrangling between Ruby's heirs and Jules Mayer, a lawyer who knew Ruby and was named executor of the Dallas nightclub owner's estate. But with the twists and turns the case has taken through the judicial system since Ruby died Jan. 3, 1967, nothing is certain. The six-person jury selected Monday was expected to hear opening statements Tuesday. The court is dealing with the questions of how to distribute Ruby's assets and whether to remove Mayer as executor. Mayer still practices law at age 82. Attorneys for Ruby's brother, Earl, were expected to question Mayer's ability to handle the estate in light of his advanced age. Potential jurors were questioned about their views on mandatory retirement and a person's professional effectiveness beyond a certain age. The most valuable asset in the estate is the .38-caliber Colt Cobra Ruby used to kill Oswald in the basement of the Dallas City Jail two days after President Kennedy's assassination here in 1963. Ruby was convicted of murder in 1964 and sentenced to die in the electric chair. A Texas appeals court overturned the conviction in 1966, citing reasons that included failure to move the trial from Dallas. Ruby died at age 55 before a new trial could be held. For years since then, Mayer and Earl Ruby have been fighting over ownership of the gun Jack Ruby bought for $62.50 in a Dallas gun shop. The gun is stowed in a bank safe deposit box. Mayer estimates it could bring $125,000 on the collectors' market. Whatever its value, Mayer contends money from sale of the gun should go to pay off Ruby's debts. He says they include the $65,000 it has cost him to handle the estate, including the expense of fighting Earl Ruby's lawsuits. Earl Ruby, of Boca Raton, Fla., who is also acting on behalf of his sister and a nephew, counters that Mayer is trying to profit from the estate. He wants the estate liquidated to pay off his brother's debts and ``wipe the slate clean.'' He also claims that Jack Ruby gave him deathbed instructions to tear up the will in which he had named Mayer executor. Apart from the coveted gun, the estate consists largely of the clothes and jewelry Ruby wore when he shot Oswald, and some personal papers. Earl Ruby said Monday that if he loses, he will ``go home and cry a little bit'' but will not appeal. Regardless of the trial's outcome, it's unlikely to be the last word on the gun matter. Last year, the Internal Revenue Service stepped into the case claiming that Ruby owed $17,000 when he died. That amount, the IRS said, has grown to $86,010 with interest and penalties. The state of Texas also claims the estate owes it $1,227 in back taxes. Earl Ruby says the IRS sacrificed any claim by waiting 22 years to act on it. Price has set a trial for February to hear the IRS claim.