When the little girl disappeared, Casey did not even report her daughter missing for more than a month. She was known to party heartily and regularly and showed no sign of regret or fear for her missing daughter until someone else made an issue of it. Casey is tried for murder.
The trial is showcased in the national media as the most recent iteration of the "Trial of the Century." Casey is eventually found not-guilty and will most probably get rich off the story through some kind of book/movie deal. The talking heads who have kept the story on the front news burner for 3 years keep talking about it incessantly even afterward.
The public is outraged.
There is no investigation of the event. In fact, Casey's right to choose to eliminate her daughter is lauded and protected by the Supreme Court as a privacy issue.
After the little girl disappears, Casey's life doesn't skip a beat. She is known to party heartily and regularly and shows no sign of regret for having ended her daughter's life. Casey is not tried for murder. There are no grounds for such a trial.
In general, the public doesn't know anything about it. Those who do, mostly couldn't care less.