LUDINGTON, Mich. (AP) — A western Michigan man has been charged with killing his infant daughter, who disappeared more than two years ago, prosecutors said Friday.

The filing of an open murder count against Sean Phillips “moves us one step closer to securing justice for Baby Kate,” state Attorney General Bill Schuette said when announcing the charge with Mason County Prosecutor Paul Spaniola.

Phillips, 23, was convicted last year of unlawful imprisonment in the disappearance of Katherine Phillips. She was 4½ months old when last seen in the Ludington area, about 80 miles northwest of Grand Rapids.

Schuette said at a news conference that “new evidence has been discovered which supports a murder charge in this case,” but provided no details, the Ludington Daily News reported.

Phillips was arraigned Friday during a videoconference with Magistrate Patricia Baker, who said she would appoint an attorney to represent him.

Prosecutors said previously that Phillips took the baby from her mother because he feared a court-ordered paternity test would show he was the father. He received a sentence of 10 to 15 years in prison and is appealing.

Katherine’s mother, Ariel Courtland, testified earlier in the case that she last saw her daughter in a car seat in the back seat of Phillips’ car.

The Daily News reported that police found Phillips about three hours after Courtland reported her daughter’s disappearance. Officers found the baby’s car seat and diaper bag in the trunk and found her balled-up, inside-out clothing in his pocket, the newspaper said.

Investigators have said that seeds and other material on Phillips’ shoes could be crucial to locating a body.

Spaniola said that since Phillips’ conviction on the related charge, detectives have spent “countless hours” on the case.

“This continuing investigation has included review of biological evidence, site visits, and the enlistment of experts from all over the world who are preeminent in their fields,” Spaniola said.

Ludington city police and the Mason County Sheriff’s Department worked on the case with help from the Michigan State Police and the FBI.

The open murder charge means a jury can consider both first- and second-degree murder.