Detective Senior Sergeant Chris Taylor from the Major Crime Squad said: "Our focus at this stage is identifying the woman.
"We are working with local, national and international partners in an effort to identify her."
Sergeant Taylor said that it was not known when the woman had died or how long the suitcase has been in the water or how it got there.
Earlier reports suggested the woman may have died in the past week, but these have not been confirmed, a police statement read.
"We encourage anyone who saw suspicious activity on the Swan River over the past week to come forward," he added.
The discovery of the body in the suitcase has led police into a murder inquiry according to an earlier report made by Western Australia police.
The grim discovery was made by fisherman the day of the Federal Election a few hundred metres from the Water Police headquarters in North Fremantle.
Police divers spent several hours working from Mosman Park jetty in search of clues, reported Perth Now.
This is the second body to be found on the shore of Swan River in East Fremantle in just over a month.
Sean Mitchell, 37, was last seen at a Murray Street beer café in Perth at about 5pm on May 20 and later that evening called to say he would be boarding another friend's yacht on Swan River.
A member of the public discovered a body in the water in the vicinity of Chidley Point Reserve in Mosman Park on Monday May 30 about 1.5 kilometres south of where Mr Mitchell boarded the boat.
A bag of Mr Mitchell's belonging were found by a diver at Blackall Reach May 22 which included personal items including the 37-year-old phone, reported The Western Australian.
A search party went out for the Samson resident on May 25 and the following day a yellow dingy believed to be used by Mr Mitchell was found on the beach at Chidley Point.
It is believed Mr Mitchell may have used the dingy to row to shore from the yacht.
Officers forensically examined the yacht and dingy but said the examination did not provide any further clues, reported ABC.
Western Australia Police initially suspended the land and air search on Monday, until they were alerted of the body by a member of the public.
Police spokesman Samuel Dinnison told Perth Now: 'It is believed the body is that of missing man Sean Mitchell, however at this time no formal identification has been completed.
"Mr Mitchell's family have been advised of this development.
"No suspicious circumstances have been identified."
The 37-year-old's family have since been notified by police and a coroners report is being prepared.
