Four-month-old Katherine was last seen on June 29, 2011 in Ludington, Michigan. She resided with her mother Ariel Courtland at the Birch Lake Apartments in the 900 block of east Tinkham.
On that same day, Ariel got into an argument with her boyfriend Sean Michael Phillips. They were sitting in Sean's silver 1998 Oldsmobile Intrigue car in front of the building with Katherine sitting in the backseat.
Ariel stepped out of the car to get Katherine's stroller from the apartment and Sean ended up driving away with Katherine in the car. The Michigan license plate number on Sean's car is BUY0298.
Ariel called Sean's cell phone when she realized he was gone, but he never responded. After realizing that Sean deliberately took Katherine & was not returning, Ariel called 911 and the police began searching for them.
A few hours later, Sean was arrested at his parents' home in Scottville, Michigan and was charged with kidnapping. His car was recovered and Sean had Katherine's clothing in his pocket, but Katherine wasn't with him & Sean refused to say where she was. He initially claimed that he left Katherine with Ariel.
Sean is a soldier with the Army National Guard and he was scheduled to be deployed in August of 2011. Reportedly, he was stressed over his deployment and other issues in his life. He is the father of Ariel's oldest daughter and was presumed to be Katherine's father as well, but Sean's paternity hadn't been proven in court by the time Katherine was abducted.
Sean felt that he couldn't afford to support two kids and didn't want to tell his parents that he fathered another child. Ariel set up an appointment at a DNA laboratory (scheduled for June 29th) which she planned to show Sean's parents, but instead of going to the lab, Sean drove himself, Ariel and Katherine to the office of the Mason County Department of Human Services where he tried to put up Katherine for adoption.
Ariel and Sean were considering putting Katherine up for adoption and even partially filled out the paperwork for it, but Ariel refused to consent to it and they drove back to the apartment which was the cause of the argument when Sean abducted Katherine.
After Katherine's abduction, a DNA test proved that Sean was her biological father. Ariel passed a polygraph regarding Katherine's abduction and she's not considered a suspect. She repeatedly visited Sean in jail after he was arrested and gave him money.
Ariel stated that she was trying to stay on friendly terms with Sean so he could tell her where Katherine was, but all Sean told her was that Katherine was still alive. Ariel stated that she & Sean often argued and once, Sean threatened to take her oldest daughter away from her if she didn't agree to put Katherine up for adoption. She thought that Sean was a good father & never suspected that he could hurt Katherine.
Authorities launched an extensive search of the area between Ariel's apartment and Sean's parents' home (the two residences are located about six miles apart). There were unconfirmed reports that blood was located in the woods near Sean's parents' home.
After three weeks, investigators discontinued the search, having found no indication of Katherine's whereabouts. The authorities are still looking for Ariel's cell phone (which was in Sean's car). The phone is described as black with a light purple strip around the display window.
Sean's attorney filed a motion to dismiss the kidnapping charge, arguing that Sean couldn't legally kidnap Katherine because he was her father & the law states that a "natural or adoptive parent" can't be guilty of kidnapping.
The prosecution argued that because the DNA testing was incomplete and that Sean denied paternity to his parents, friends & co-workers, he wasn't Katherine's "natural parent" at the time of her abduction.
In the end, the judge sided with the defense and the prosecution reduced the charges against Sean to false imprisonment and parental kidnapping. In April of 2012, he was convicted of false inprisonment & was sentenced to 10 to 15 years in prison. A kidnapping conviction could've resulted in a life sentence.
Following Sean's sentencing, police said that they were treating Katherine's disappearance as a homicide. Allegedly, Sean wrote a letter to Ariel that was leaked to the media in September of 2012. The letter stated that Sean accidentally killed Katherine.
During that same month, Ariel filed for a license to marry Sean, stating that she wasn't doing it for love, but she thought that it would help her find out what happened to Katherine. At the present time, Ariel is not allowed to visit Sean in prison because she is legally a victim of his.
The authorities have not said whether or not they're filing additional charges against Sean. Katherine's disappearance remains unsolved and it will remain open until she is located.
Katherine is described as having light brown hair & blue eyes. She has a cleft chin. She was last seen wearing a one-piece white outfit with black polka dots, black & pink flowers and pink shoulder straps. Her nicknames are Kate and Katerbugger.