I think that the first report of anyone seeing the burned campsite was at about 2pm the following day, when a hiker saw it.
As GL was apparently on the move that same night, the police have been able to narrow down the time to sometime prior to midnight.
"Police are now certain the couple died within 18 hours after Mr Hill's last message, as a passing hiker saw the burned-out campsite about 2pm the next day."
Twist in case of two missing campers as cops KNOW who was near campsite amid affair | Daily Mail Online
The vehicle was captured on roadside cameras driving on The Great Alpine Road and matched a description of a car witnesses saw parked near their campsite and heard leaving the area about midnight.
New clues in mystery of missing campers Russell Hill and Carol Clay