The reason cud b bcoz of the story writer.Yes,the story writer Sonali Jafar is d writer of both d shows.In BI she shares with another writer also.
And now heard in SBS(which cnt b completely true) dat Mihir(hero's friend) is d culprit behind d accident.
So the culprit in BI has to b sm imp character,May b Rizwan or Suri.
I m sorry for mentioning other show here but just wanted to share my thoughts on this.