Hi everybody,

I didn't find a better place to ask my question, I hope here is okay.

I am trying to describe a voice, I kind of know in my head what should it sound like, but I can't pick the words (English's not my first language).
Voice can sound oily, charming, etc. I want to have something between those two, as to opposed to uncultured and gruff. Or if I say cultured/uncultured it has to be accent, not voice? I'm not sure.
Just give me some ideas about adjectives, if you can think of any, please.

Another question that I have is about an official phrase in Br English that a policeman would say when arresting someone.
"I'm arresting you in? the suspicion of? murder" - sounds strange. Do I have wrong prepositions?
"You are under arrest for/in relation to the murder of...?" - but doesn't it mean that the police is already decided he's guilty? I don't want to have that. When people are arrested, they generally have not been proven guilty yet.

Does anyone know what British police officers actually say?

I am grateful for any input.