PORTLAND – A Superior Court judge has ruled that she will preside over a Sabattus man’s murder trial, rejecting a claim that her previous work with domestic violence could create the appearance of bias in the case.

Daniel Roberts’ attorney, Leonard Sharon, had asked Judge Joyce Wheeler to step down from the case because of her involvement in domestic violence issues.

Roberts is being held without bail in the murder of his ex-girlfriend, Melissa Roberts.

Roberts admits fatally shooting Mendoza last August, but claims he was acting in self-defense. Prosecutors say that Roberts ambushed Mendoza, and that her death was the last act in a violent relationship.

In her decision filed in Androscoggin County Superior Court in Auburn, Wheeler called it “absurd” to suggest she would be partial in Roberts’ trial.

She explained she was involved in the development of a domestic violence court when she was a District Court judge. But that involvement, she said, would not interfere with her ability to preside impartially in Roberts’ case.

Sharon said Gov. John Baldacci once referred to Wheeler as “an advocate for victims of domestic violence.” Such a distinction, Sharon said, makes her a bad choice to preside over Roberts’ case.

“You don’t want an advocate for a judge,” Sharon said.

“I’m not saying she’s partial, but at some point the question becomes whether there is an appearance of partiality.”

Sharon said he would review Maine law to see if he could appeal the decision right away, or if he would have to wait until the case is completed.

At the time of the shooting, Roberts and Mendoza, who was 29 and living in Tustin, Calif., were locked in a bitter custody dispute over their 2-year-old daughter.

Mendoza had sought protection from abuse orders against Roberts and was in Maine to attend a child custody hearing.

Roberts has claimed he shot Mendoza because she threatened to kill him, their daughter and herself when she came to his home.