Anyone can file a notice of claim and begin the process of suing.
However the Police have a common right of inquiry with the public.
Most states require resonable effort to contact parents/guardian...
Define "questioned by police." There are no restrictions on officers simply talking to minors - more has to be known about the circumstances. Is the juvenile in custody? Is the juvenile being talked...
The only way to be sure is to check your state laws, but there are many scenarios where it is considered perfectly acceptable, especially under some situations and also especially with consent.