Did the writers change the circumstances of Marian's death?

When Robin and OQ were first introduced, was Marian meant to have been killed sa pamamagitan ng Regina, as in the original timeline which was altered in the S3 finale? Or did the writers change that backstory? Because if that was always how Marian died, I'd find it a bit strange that Robin could ilipat on with her killer, without even mentioning what had happened or confronting Regina about it. I'd also find it strange that he'd never learn how Marian died, or believe she'd died in another way, ibingiay how the entire village saw her being arrested.