A 23-year-old man has been charged with the murder of his infant daughter who disappeared over two years ago from Mason County, Michigan.

Sean Michael Phillips was arraigned Friday for allegedly murdering Katherine Phillips on June 29, 2011. “Baby Kate” was 4 ½ months old when she was last seen that day.

According to Associated Press, Philips was convicted of unlawful imprisonment in her disappearance in April 2012 and is already serving 10 to 15 years.

Ariel Courtland, the infant’s mother, testified last year that she last saw her daughter in the back seat of Phillips’ car. MLive reports that Phillips allegedly wrote a letter to Courtland while in prison saying that he accidentally killed the baby when he violently pulled her car seat out of his car.

Courtland attended the arraignment and news conference but did not want to comment.

"Hopefully he has been finally charged. It would be nice if they find my granddaughter,” said April Lange, Courtland’s mother.

Phillips’ probable-cause hearing is scheduled for Oct. 16.