The man who police call the "canal killer" is expected to appear in court for a preliminary hearing Tuesday morning.
Phoenix Police are investigating a third possible victim 13-year-old Brandy Myers even though her body has been found.
Miller's ex-wife, Amy, says Bryan admitted to killing a young girl years ago and it matches Meyer's disappearance story.
"There was a young girl, who had come to his door trying to deliver Girl Scout Cookies which he unfortunately never ordered any and she had come to the door by mistake," said Miller.
Miller said she didn't believe her husband at the time.
"He is a manipulator. He was able to play that really good guy. But I've also seen the side of him that could have easily murdered those women in the way they say they were murdered," said Miller.
Police say they are strongly eyeing Miller for Myers' disappearance.
Miller is also being looked at for the death of 16-year-old Shannon Aumock. She was found by the Central Arizona Project Canal, coincidentally, when crews were searching for Myers back in 1992.
Miller's trial is not scheduled to begin until April 2017.