Eclipso then attempts to kill Mary, but finds that she is too strong.

He said thoughtfully, "So you're trying to find out who killed Mary?

It doesn't seem possible, if you take my meaning, that anyone could have killed Mary.

However, he would rather kill Mary than let her live without him.

It looks like it might be the weapon that killed Mary.

It couldn't have been Mohan, not if he killed Mary, and the book was in your room.

These become more prevalent as time goes by, including a nightmare where Brown kills Mary in a similar fashion to how he killed his wife.

Bill sees the gun in his hand, and is led to believe that he has killed Mary.

Eclipso retrieves the diamond and attempts to kill Mary, only to find that she is too strong for her.

Throughout the song, backed by the video, it is unclear and thus left to the listener/viewer to decide, who killed Mary.