The inquest was told Ms Roberts had been at a nightclub in Pwllheli and left at about 01:35 in the morning, heading towards a taxi rank.
However, CCTV footage showed there were no taxis there, and Ms Roberts began walking the three miles towards her home in the nearby village of Y Ffôr.
About 40 minutes later she was struck by a car driven by David Wyn Jones on the main A449 road.
Crash investigator Ian Thompson said he could not say how she came to be lying in the road, but speculated she may have stumbled and fallen on an uneven surface.
Mr Jones told the inquest that he saw what appeared to be an object on the road, but it was not until he was “really close that we realised it was something more”.
“As soon as I realised there was something there I braked immediately,” he said.
He described telling his partner “I think I’ve hit something, I think it was a person”.
