Hartford - Eduardo Santiago may or may not have killed anyone, yet he sits on Connecticut's death row for his role in what prosecutors say was a murder-for-hire plot involving two other men in which the bounty was a pink-striped snowmobile with a broken clutch.

Jurors who convicted Santiago in 2004 for the killing of 45-year-old Joseph Niwinski in West Hartford in December 2000 were split on whether he was the one who pulled the rifle trigger, but convicted him of aiding in a capital felony, aiding in a murder and other charges. The two other defendants pleaded guilty and are serving life in prison.

Santiago appealed the convictions and death sentence to the state Supreme Court, which is scheduled to hear arguments in the case today.

His lawyer, Assistant Public Defender Mark Rademacher, said there were a series of problems during the trial and deliberations including juror misconduct, the judge improperly withholding some evidence about Santiago's troubled childhood, faulty instructions to the jury and the unconstitutionality of the death penalty law.

"It's just a case of the death penalty run amuck," Rademacher said. "There's just no reason for this case. It should have been just a run-of-the-mill murder case."

State prosecutors plan to argue Wednesday that there's no merit to any of Rademacher's claims and that Santiago's convictions and death sentence were justified. They also note that state law allows for the death penalty for aiding in a capital felony.

"There was no dispute that he was present," said Senior Assistant State's Attorney Majorie Allen Dauster. "It doesn't matter if he pulled the trigger or not."

Niwinski's brother, Frank Niwinski Jr., said he planned to attend the Supreme Court arguments. He said the appeal is bringing back the pain of his brother's murder and he believes Santiago should get the death penalty, despite the issues raised by the defense.

"Whoever murdered my brother, it didn't ... matter," said Niwinski, 62, of Bristol. "They did it. They planned it. They executed it. I don't really care who was the shooter.

"I love my brother and I feel so bad that he was murdered at such a young age," he said. "Why does any person have the right to take someone else's life? They should not abolish the death penalty. I think we have to start setting an example."

The Supreme Court arguments come as state lawmakers are considering abolishing Connecticut's death penalty law. Ten men are currently on the state's death row.

Prosecutors say the plot to kill Niwinski was hatched by 46-year-old Mark Pascual, who owned a shop in Torrington that sold snowmobiles, boats and ATVs. Authorities say Pascual was infatuated with Niwinski's girlfriend, believed Niwinski was abusing her and wanted him dead. They also say Niwinski owed Pascual about $5,500. The two met at a marina and had gone boating together.

Pascual knew Santiago because Santiago's stepfather ran a restaurant next to Pascual's shop. Police say Pascual asked Santiago if he knew anyone who would kill someone, and Santiago said he would do it for the broken snowmobile that sat in Pascual's shop. Santiago got his friend, Matthew Tyrell, to take part in the plot, police said.

On a Wednesday night, Dec. 13, 2000, all three men went to Niwinski's home in West Hartford. They had a rifle with a silencer made out of a 2-liter soda bottle with shredded paper towels inside, and Santiago had etched the name "Joe," Niwinski's first name, on some of the rifle cartridges, police said. Pascual stayed outside, while Santiago and Tyrell went inside, authorities said.

Niwinski was sleeping when he was shot in the head. Santiago told police that Tyrell pulled the trigger, while Tyrell testified at Santiago's trial that Santiago was the shooter. Defense lawyers say a juror told them the jury was split on whether Santiago fired the rifle or not.

After the jury convicted Santiago of capital felony, it had to weigh aggravating factors listed by the prosecution against mitigating factors listed by the defense to determine if Santiago should die by lethal injection. The jury considered one aggravating factor - that Santiago committed the crime in exchange for something of value - against 25 mitigating factors.

Jurors determined that the aggravating factor proven by the prosecution outweighed one or more mitigating factors proven by the defense and recommended that Santiago be executed.

Rademacher wrote in Santiago's appeal that a juror told defense lawyers that jurors were disappointed that the state had only one aggravating factor and improperly made up other aggravating factors on their own to consider. The juror also said, according to Rademacher, that jurors failed to consider whether Santiago was the shooter during the penalty phase, while another juror said some panel members erroneously rejected a mitigating factor.

The appeal said a judge failed to fully investigate the juror misconduct allegations.

The appeal also claims the trial judge wrongly refused to release the entire file on Santiago's childhood that was compiled by the state Department of Children and Families, which the defense says amounted to withholding evidence of other mitigating factors.

The DCF records document the mitigating factors in Santiago's grim childhood, which included beatings by his mother and stepfather and sexual molestation, and his nine-year journey through foster care, psychiatric hospitals, orphanages and shelters, Rademacher said.

The appeal says Santiago's conviction for aiding in a murder-for-hire was improper.

Connecticut's last execution came in May 2005, when serial killer Michael Ross was put to death.