But I'm "only a witness"!
I often get phone calls from parents who tell me that their son or daughter is at the police station being interviewed "only as a witness", not as an accused. The police have the son or daughter in a closed room with no parent present and no advice to the young person that they can leave or that they can phone a lawyer.
Sometimes police will bring a clerk into the interview room who takes a "KGB" statement under oath. The term "KGB", in this context, has nothing to do with Russian secret police (it's the name of a case R. v. B. (K.G.), 1993 CanLII 116 (SCC),  1 SCR 740), but it scares witnesses anyway. The clerk will then administer an oath and the young person will give a statement on video. Police do this often in domestic assault cases, where they want to make sure that the witness doesn't recant and protect a family member or partner when they actually get on the witness stand. A witness who gives evidence in Court that contradicts the KGB statement can be prosecuted criminally for giving contradictory evidence under oath. That's why police do it. Members of the public need to remember that if they haven't been arrested, and they don't feel comfortable with what the police are doing, they can simply ask to leave. They don't have to give an oral, written, or KGB statement if they don't want to.
The witness who is in police hands can also ask to talk to a lawyer. The police may not respect that right but it can't hurt to ask to get some independent advice from a lawyer or a parent to know just where you stand. Can you leave? Can you say "no" to the KGB statement? That's not a parent's right to ask - the right belongs to the young person.
Our biggest concern always has to be that a witness interview will at some point become an accused young person interview. The young person who says they were a witness to a crime may end up being charged as a party to that crime. The young person who blames another young person for a crime may end up getting charged with public mischief if police don't believe them. The young person who changes their story over time or during subsequent interviews may end up being charged with something.
Maybe it would be a good idea for the parent or the young witness to call a lawyer first. And ask: "Is this a good idea?"