Police are investigating how a day at the races ended with a 36-year-old woman being taken to Cairns Hospital with serious head injuries.
The woman, a Cairns local, was found lying in a culvert at Clarkes Creek on Saturday about 9pm after a man leaving nearby cinemas alerted officers in the area who were conducting random breath tests.
Senior Constable Russ Parker from the Cairns District Crime Prevention unit said officers were investigating the woman's movements and how she ended up in the drain.
"We are very keen to narrow down her movements," he said.
"We are looking for any motorists with dashcam footage, especially outbound along Mulgrave Road between 7pm and 9pm on Saturday, to come forward."
Sen Constable Parker said police were investigating if the woman fell about 2 metres from the top of the railing of the bridge over the culvert.
"At this stage there is nothing to indicate anyone else was involved," he said.
"She has serious head injuries and other undisclosed injuries and we have not been able to talk to her at this stage.
"We are very concerned for her welfare and information from the public will be important to the investigation."
Police thanked the man for approaching police, saying the woman may have been there for much longer without medical help if he had not come forward.
Police also know the group the lady was at the races with earlier in the day and they have been assisting with the investigation.
"Walking home after a day out can be fraught with danger," he said.
"This is a reminder to people when they are out with friends to ensure they get in a taxi or get home safely."
The woman is described as Caucasian in appearance and was wearing a white, pink and purple floral dress and a large pink ‘racing’ style hat with features and white high heeled shoes.
Sen Constable Parker said she would have 'stood out' to motorists as she was walking in the bike / pedestrian lane on Mulgrave Road towards Earlville shopping centre.