Police said Elena Zyalkova, 38, was in a dazed state and walking on the road to Mab Prachan reservoir in tambon Nong Prue when she was found, reports Bangkok Post.
Police and rescue workers were called to the scene around 9.30pm, Lt Chatchai Rakkhamchop, deputy crime suppression chief at Nong Prue Police Station, said on Thursday (May 19).
Ms Zyalkova was wearing a jogging suit and had head injuries. There were bruises on her neck and abrasions all over her body. When asked she could not remember what happened.
The police examined the road and nearby areas and found a trail of blood stains leading about 10 metres into the forest beside the road, along with a pair of running shoes and a mobile phone, both hers.
Motorist Kosol Chomchuen, 36, told police he was going home when he came across the woman walking along the road. She signalled for help. The woman was bleeding and he immediately stopped and called police. The injured woman was taken to Bang Lamung Hospital for treatment.
Local and tourist police are investigating. Yet, police said details were sketchy. It was not clear why she was attacked and what her assailant wanted. She would be questioned when she had recovered sufficiently.