BOSTON (AP) – Convicted killer Gary Sampson asked a federal appeals court Wednesday to overturn his death sentence, arguing that a judge gave confusing instructions to the jury that condemned him to death.

Sampson, a drifter from Abington, pleaded guilty in the killings of Jonathan Rizzo, 19, of Plymouth, and Philip McCloskey, 69, of Taunton, during a weeklong crime rampage in July 2001. He also confessed to killing a third man – Robert “Eli” Whitney, 58, in Meredith, N.H. – and was sentenced separately in that case to life in prison.

A federal jury in Boston gave him the death penalty in December 2003 after hearing weeks of testimony about how Sampson carjacked each of the men, then fooled them into thinking he only wanted to steal their cars before slitting their throats.

Sampson is the first person sentenced to death in Massachusetts under the federal death penalty law. Massachusetts, which does not have a death penalty, has not executed anyone in more than half a century.

Sampson’s defense team, arguing before a three-judge panel of the 1st U.S. Circuit Court of Appeals, said the judge who presided at Sampson’s sentencing hearing confused jurors when he told them they must each decide for themselves what it means for aggravating factors to outweigh mitigating factors “sufficient” enough to justify a death sentence.

Sampson’s lead attorney, David Ruhnke, said U.S. District Judge Mark Wolf “invited jurors to apply their own standard – their own idiosyncratic standards – as to what was sufficient to sentence him to death.”

Steven Lane, an appellate lawyer with the U.S. Department of Justice, said the federal death penalty statute does not set a specific standard, but instructs jurors to balance aggravating factors against mitigating factors when deciding whether to impose the death penalty.

Lane argued that Wolf’s instructions actually favored Sampson because the judge also instructed the jury that it must find unanimously and beyond a reasonable doubt that the death penalty was justified based on the weighing of the aggravating and mitigating factors.

“The question of confusion doesn’t get the defendant anywhere if the confusion or the misstatement was in his favor,” Lane said.

Sampson’s attorneys also argued that the judge should not have allowed gruesome crime scene photographs that played to the emotions of jurors. The government argued that only a small subset of the crime scene photographs were shown to the jury and that they illustrated the heinous nature of Sampson’s crimes.

The court did not indicate when it would rule.

Ruhnke said that if Sampson loses this appeal, he will ask for a hearing before the full 1st Circuit – comprised of six judges – and would eventually take the case to the U.S. Supreme Court, if necessary.

More than two dozen relatives and friends of Rizzo and McCloskey attended the hearing. Afterward, Rizzo’s father, Michael Rizzo, said he found Sampson’s arguments “preposterous.”

“It’s unfortunate that we have to relive all the feelings and the emotions of the trial,” he said.