The body in the woods plot

I'm half way through my new book. It has very major events thought the book. The first time is when they discovered body in the wood while looking for someone else. This sets up the story for the three kids. Then the cops came and Ruby one of the three kids who discovered the body think it is a serial killer because a week back a black old women died strangeled like the girl. The cop don't believe her because the two victims are from different races. This may not seem like a connection, but this soon leads to the second major event. At this point in the book the killer as struck again this time an Asian girl. Then when Ruby trying to figure out what the connection is and when she say it out loud  Alexis figures it out. That the killer wants a Collection of each race so then they go looking for a Hispanic girl who is homeless. So that as far has I got.