The state Supreme Court on Monday refused to postpone the execution of serial killer Michael Ross (search), dismissing another request to halt what would be New England's first execution in 45 years.

The high court upheld an earlier ruling that Ross was competent to make his own decisions, rejecting arguments that the waiver of his appeals was involuntary.

Ross, 45, admitted killing and raping eight young women in Connecticut (search) and New York in the early 1980s. He decided last year to forgo all appeals and has been seeking to expedite his death sentence, which is scheduled to be carried out early Friday.

Thomas Groark (search), a special counsel appointed by a judge in February to argue that Ross was incompetent, did not immediately return a call seeking comment Monday.

Earlier in the day, Ross' sister asked a different judge to allow her to intervene against her brother's wishes to stop his planned execution.

Donna Dunham's request follows similar failed attempts by Michael Ross' father and the state's public defenders to file appeals on Ross' behalf.

"He does not endorse his sister's action in any way," said Ross attorney T.R. Paulding. "He wants nothing to do with this."

Dunham, one of Ross' three siblings, lives in Texas and was not in court Monday. Ross has no relationship with her, Paulding said.

A call to Dunham was not immediately returned.

Her attorney, Diane Polan, argued that Ross was not mentally competent to give up appeals of his death sentence. She said the harsh conditions of his confinement, coupled with his mental health problems, made his decision involuntary.

Rockville Superior Court Judge Jonathan Kaplan said he would decide Tuesday whether to accept the petition.