What is the book about the teenager and the police?

The teen girl has blue hair. I think she used to have cancer. One night she was smoking with this one guy on the railroad. The police finds them and and two other people there. Throughout the book she has drive around with the officer. AT the end she falls in love with him. The police doesnt like the train tracks because thats where his brother died.What is the book about the teenager and the police?This book isn't all about understanding police officers altogether. ... I too, would highly recommend this book to be read by all teenagers.