Young couple goes on van tour of US, boy comes back with van - no girl

Speaking theoretically- I know this isn’t what happened- but say Brian assaulted Gabby but did not know if she was dead
Then he went and told his parents but they didn’t say anything
would they be complicit in the actual death or just in some lesser charge?
(Also would time of death matter? Like if she’s already dead when Brian confesses but nobody knows yet?)

“Charge” refers to crimes - there are possible accessory charges they might face depending on what actually happened . . . which I don’t think any of us knows.

But “wrongful death” is a civil claim for damages (tort). I don’t see how your hypos result in civil liability for the parents.