To add...
I remember posting that it is possible the accused took the victim's body late in the afternoon/early evening to conceal.
(I wrote about dusk approaching)
And it seems Police's theory is that he drove with the body AFTER 5 pm.
AFTER tossing the phone to the dam!!!
My Goodness!
Was he (allegedly) keeping her in the car for soooo many hours?

8 am - 5 pm
Or was the victim relocated?
But,
in case of relocation,
the chances of being witnessed increase.
OR
The attack allegedly happened when the accused was returning home on foot
(and had his phone - pings in the are of the crime),
and
later returned with a car,
retrieved the body
but left his phone at home
(no pings to lead to Samatha).
Allegedly.
JMO