Matthew, who's accused of killing University of Virginia student Hannah Graham and could face the death penalty
, now says the judge who's been tapped to decide his fate has a conflict of interest.
In a motion filed this week, Matthew's attorney said Judge Cheryl Higgins should recuse herself from the case because of her previous involvement with the case and her family's connection to Graham.
Higgins has an immediate family member who attended a vigil for Graham, attorney Douglas Ramseur said, and her daughter attends the University of Virginia. In addition, the defense attorney argues that because the judge was involved in securing search warrants for authorities against Matthew, that will cause a conflict of interest.
"The defense anticipates there will be significant and extensive litigation over the use of search warrants in this case," he said. "Judge Higgins is naturally predisposed to uphold the validity of the warrants due to her personal involvement."
Matthew is "on trial for his life," Ramseur said, and "when a defendant's life is at stake, a court must be particularly sensitive to ensure every safeguard is observed."
Higgins did not immediately respond to a request for comment from CNN.
In court papers filed last month in response to questions from Matthew's attorney, she acknowledged that she'd signed search warrants in the case but said she did not recall the details. She also acknowledged that a family member had attended a vigil for Graham, but added that the vigil occurred before Graham's body was found and before authorities knew she was dead.
Graham, 18, went missing before dawn on September 13 after she was last spotted on surveillance video in Charlottesville's Downtown Mall area.
In October, authorities found her skull and bones on abandoned property eight miles from where the college sophomore was last seen.
Surveillance video and other accounts led authorities to identify Matthew as a suspect in Graham's disappearance.
Matthew, a 33-year-old former cab driver, was taken into custody on September 24 on a beach in Galveston County, Texas, about 1,300 miles away from where Graham was last seen.