AUBURN – A Sabattus man who claims he killed the mother of his child in self-defense is seeking to replace the judge assigned to his murder case.

In a motion filed in Androscoggin County Superior Court, Daniel Roberts said Justice Joyce Wheeler should not preside over his trial because she may be biased.

Roberts’ lawyer, Leonard Sharon, wrote that Wheeler had, during a bail hearing, “indicated that she did not believe the defendant’s version of events and felt that he had lied to the police.”

Sharon wrote that Wheeler has a long history of advocating for victims of domestic violence. That activism should disqualify her, he wrote.

“While undoubtedly a very worthy cause, (it) does create the appearance of partiality.”

If Wheeler rules against his motion, Sharon said Monday he’s not sure whether he’s allowed to appeal her decision to a higher court before a verdict in the case.

Before the shooting death of Melissa Mendoza, 29, she and Roberts, 36, had been embroiled in a fierce custody dispute over their 2-year-old daughter, Savannah Marie Roberts.

Mendoza had filed several protection from abuse orders against Roberts, most recently in June 2005. She was denied a permanent order because she failed later to show up in court.

She had written in supporting documents that Roberts had put a gun to her head several times and said she was afraid he or one of his friends would hurt her.

In August 2005, she was found shot dead in the back of the head at Roberts’ Sabattus home.

After the shooting, Roberts said she had come to his house and threatened to kill him, their daughter and herself. He said she was armed with a .38-caliber snub-nosed revolver she had taken from his house.

Roberts has been held in jail without bail since his arrest in December 2005. No trial date is set. A flurry of motions were filed last week by both sides. Besides his effort to have the judge step aside, Roberts is seeking to:

• dismiss the murder indictment against him because evidence favorable to his defense was allegedly withheld from the grand jury;

• get access to items belonging to him that were taken by police so that he can have them independently tested in a lab;

• have his trial moved out of Androscoggin County due to pretrial publicity; and

• have the jury view the scene of the shooting at 1 a.m., the time Mendoza was killed.

Prosecutors want to:

• make transcripts of grand jury testimony bolstering the state’s case available to both prosecutors and the defense;

• have the jury view the scene of the shooting; and

• set aside any attorney/client privilege that existed between Mendoza and her lawyers so they can testify about the ongoing custody dispute and help explain her actions.