Convicted killer Michael Scott DeCorso will not get a new trial and will spend the rest of his life in prison for raping several women and killing a Payless shoe store clerk in 1994.

In a decision released Friday, the Utah Supreme Court upheld DeCorso's conviction on aggravated murder and denied his appeal for a new trial. DeCorso, 29, was convicted by a 3rd District Court jury in 1996 of killing Margaret Ann Martinez, 50.The jury sentenced him to life in prison without the possibility of parole. Shortly after being convicted of murdering Martinez, DeCorso pleaded guilty to rape and assault in four other cases involving separate women.

Just after closing a West Jordan Payless store on Feb. 15, 1994, Martinez was approached by DeCorso, who had remained in the store posing as a customer. DeCorso robbed Martinez, took her in the back room where he gagged her with duct tape, beat her, sexually assaulted her and stabbed her several times with scissors. He then fled the store with a pair of boots, a pair of tennis shoes and about $800 in cash.

Martinez's partially clothed body was found after her husband called police when she didn't return home from work. A coroner ruled Martinez suffocated from the duct tape.

Police arrested DeCorso and charged him with the murder after fingerprints taken from evidence of a later robbery at a Draper Payless store matched fingerprints on the duct tape.

In his appeal, DeCorso argued that evidence from the Draper store robbery was prejudicial and should not have been allowed in his murder trial.

However, the Supreme Court ruled that the trial court was correct in allowing the evidence because it was offered for the sole purpose of establishing the killer's identity. The evidence was strong that DeCorso committed the Draper store robbery, and a fingerprint from evidence in that robbery connected him to the West Jordan robbery. The two crimes also had many similarities and were "signature-like," the court said.

The court also ruled that evidence from the Draper store robbery did not prejudice the jury because the crimes committed at the Draper store were relatively minor compared to the crimes at the West Jordan store.

"DeCorso did not harm or injure his victims at the Draper Payless," the court wrote.

The court also ruled that testimony from a jail-house informant who said DeCorso admitted torturing and sexually assaulting Martinez was not prejudicial because there was enough other evidence supporting the claim.

The decision also says photographs of Martinez's corpse were not prejudicial because they were needed to show the heinous way she was murdered, which must be proven under the aggravated murder statute. The justices also denied DeCorso's claims that a police lineup identification should have been suppressed and that evidence seized during raids of his storage shed and parents' home should have been suppressed.