The state Supreme Court on Wednesday rejected an appeal from the sister of serial killer Michael Ross (search), in what has become another unsuccessful attempt by outside parties to stop the first execution in New England in 45 years.

Diane Polan, attorney for Donna Dunham (search), Ross' sister who was rebuffed this week by a state court, argued Wednesday that Ross' mental problems combined with the pressure of spending years under the harsh conditions of death row have made it impossible for him to make a voluntary choice.

"Saying he is competent is not the same as saying he's capable," Polan said.

Attorney T.R. Paulding has anticipated a flurry of legal petitions as time runs out on Ross' life.

One of them was filed in federal court earlier Wednesday on behalf of a state inmate who claimed the execution would cause a wave of suicide attempts among troubled Connecticut (search) prisoners. A hearing on that suit was scheduled later in the afternoon. A federal judge was expected to hear that case late Wednesday afternoon.

The high court earlier this week upheld Ross' mental competence in another appeal. It has also previously rejected requests by Ross' father and the state's public defenders to intervene and file appeals against Ross' wishes.

Prosecutors argued that once a court has ruled that Michael Ross is ruled competent to make his own decisions, only he can claim that his decision was not voluntary.

Polan on Tuesday filed another similar petition in federal court. That petition was expected to be heard if the state Supreme Court rules against her.

In addition to the court fights, the state Department of Public Health has received formal complaints from at least four doctors asking it to investigate the planned execution.

The department rejected complaints from three Connecticut physicians alleging numerous medical, ethical and legal problems with the state's lethal injection procedures. A fourth doctor, from Ohio, alleges that the Department of Correction and its clinical director improperly volunteered to train Ross' execution team in the medical procedures needed for lethal injection.

Paulding said Tuesday that because the court has left no doubt that Ross is competent, others will have a hard time stopping the lethal injection.

"The issue of competence was the only potentially valid issue that would allow any of these interlopers to get their foot in the door," he said. "That mechanism for them to get their foot in the door seems to be closed."

Ross, 45, is scheduled to die at 2 a.m. Friday. He was sentenced to death for murdering four young women in eastern Connecticut in the early 1980s and has confessed to four other murders in Connecticut and New York.

Last year, he decided to end his appeals and accept his death sentence. He was hours away from being put to death in January, when Paulding, under pressure from a federal judge, asked for a new hearing to examine his competency.

Edwin Shelley, whose 14-year-old daughter Leslie was killed by Ross in 1984, said he's hopeful it will happen this time.

"None of the people who are filing these appeals have standing," he said. "These are all frivolous lawsuits brought by uninterested parties. They should be made to repay the state of Connecticut for the money wasted defending against them."