[F] My daughter died in September of Liver Failure. She was found by her "boyfriend". He was quoted as saying she must have died at 13:00. The EMS showed up at 15:00. Autopsy completed next morning. Rigor Complete and wearing off and livor is dependent. What exactly does this mean? Would 13:00 be an accurate time of death?

Rigor mortis refers to the state of a body after death, in which the muscles become stiff. It commences after around 3 hours, reaching maximum stiffness after 12 hours

So yes that could be close, remember time of death is always an estimate unless someone was there, Often give or take a couple hours

Rigor Mortis is a phase the body goes through after death...
It starts 2 - 3 hours after dying. The body goes through a chemical... it's called putrefaction. Rigor mortis lasts 24 - 48 hours, it all depends on the temperature and humidity the body is in.
If the Pathologist states that rigor is wearing off, the body died over 12 hours prior. With Rigor mortis, the peak is usually at 12 hours, about.
It is all judged on the stiffness of the body. If it's stiff to the point of breaking when moved, then it would have died within the past 12 hours.
Now you have to know, they can not tell you the exact time of her death, only about.
If you have other questions regarding this, please feel free to ask me.