I just did a rescan of the thread to check some facts. To summarize some things for the late entrant and those going back and forth on things:
The "trouble" started with the DM at 60' and the victim at 80'. The claim is that the victim was below and the DM was unaware until signaled by another diver. The DM attempted tank banging and then followed when the victim didn't respond. Contact was made by 100' and the DM and victim remained in contact to 140', at which point the DM ceased to attempt rescue. During the contact, the victim is said to have resisted assistance and pushed away the DM. People have been talking about initiating a rescue at 140', but that's not the case here. The rescue was initiated in the 80-100' depth range and lack of effective action allowed it to continue to 140'.
By the accounts, a pair of divers were at 60' and told the DM that she had lost contact with her buddy. Someone claimed visibility in the range of 100'. That being the case, that pair of divers were in position to see what went on between the DM and the victim. Whether or not they stayed in position or watched the events unfold has not been presented, nor have that pair of divers posted here. There may be eye witnesses to the whole event, but we don't know.
The question of the DM's role remains a question to me. Two parties say that the DM was specifically hired to buddy with the victim. Another says that the DM was hired by the victim and her husband jointly. I tend to believe the former, but the DM may have thought she had responsibility for the husband as well, or that catering to both might improve their enjoyment of the dive as well as her tip.
There is also some question as to whether the DM was hired for this job by choice, or required by the dive operator. The question has been asked and assumptions were made that it was a requirement, but no answer has been given.
The age of the victim was given as 68 in one place, and MEG DIVER said he thought she was around 50. I don't know that anyone has come back to conclusively resolve that question.