Police are still treating Winfield's death as unexplained and have called for sightings of a black Subaru station wagon parked at the scene at the time the woman was seen playing with the two dogs.
It's unclear if the station wagon, reportedly playing loud music at the time, belonged to Winfield but a police spokeswoman confirmed it was the same one towed from the scene about 7pm.
Waikato Police wanted to hear from anyone who had seen the black Subaru station wagon parked on the banks in a reserve on the river side of Ann Street in Hamilton yesterday afternoon.
Police would like to hear from anyone who saw a black Subaru station wagon parked on the banks of the Waikato River yesterday.
They said Winfield was believed to have been throwing a ball and playing with her two dogs on the river bank.
"Loud music was reported to have been coming from the vehicle throughout the afternoon.
"Miss Winfield has later been found deceased in the Waikato river a short distance from the vehicle."
Dogs appear to have alerted members of the public to the woman's body.
Her body was discovered by a member of the public at a spot near Ann St popular with runners and cyclists.
A nearby resident, who did not wish to be named, was at her home overlooking the river when she spotted a pair of "agitated" dogs about 4.30pm on Wednesday, she told Fairfax.
"There were dogs - one brown, one black - running around on leashes before the police arrived.
"It seemed strange that they were running around with their leads and we couldn't see anyone, just some walkers coming.
"They obviously knew, they were up and down the bank all the time, yapping, then someone took control of them."
An investigation has been launched while police have expressed their condolences to Winfield's family and friends .
Any sightings of the vehicle or information can be passed on to Detective Sergeant Terri Wilson of the Hamilton CIB on (07) 858 6200 or anonymously via Crimestoppers on 0800 555 111.
