I'm currently on the last season of The L Word, and I'm frustrated with the unresolved mystery around it. Personally, I think Jenny probably killed herself. I don't think anyone in the group has it in them to premeditate and commit murder, and since season one Jenny has been going through a downward spiral of emotional breakdowns and mental illness. At the point of her death she had already ruined all of her relationships with everyone. She also loved to be the center of attention and spark drama, so it seems very Jenny-like to cause mystery even in death, making basically everyone she knew a suspect.
I think she fell off the stairs and drowned. Either that or Sounder came back from the dead to get revenge.
