skydhash parent
Git blame can do a lot in those situations. Find the general location of the bug, then assign everyone that has touched it to the ticket.
Is that really something you are doing in your job?
Most of my teams have been very allergic to assigning personal blame and management very focused on making sure everyone can do everything and we are always replaceable. So maybe I could phrase it like "X could help me with this" but saying X is responsible for the bug would be a no no.