The husband of an Indian IT professional stabbed to death in a Sydney park called on Thursday for the killer of a "beautiful soul" to be brought to justice.

Prabha Kumar, 41, was knifed in a brutal attack while speaking by phone to husband G. Arun Kumar in India on Saturday night.

"I cannot describe to you the pain I presently feel," the husband told reporters after rushing to Sydney.

"My wife was a most caring and beautiful soul. I want whoever killed my gorgeous wife to be brought to justice."

His wife's brother Shankar Shetty also attended a police press conference to make a public appeal for information about the murder, with no suspects so far identified.

"I'm still coming to terms that I've lost my sister," Shetty said. "She will never see her daughter grow up."

Kumar's husband flew to Australia on Monday from India, where both he and their nine-year-old daughter live.

A task force has been set up to investigate the murder, which happened just 300metres(yards) from her flat, but no motive has been established or arrests made, police said.

"There was no evidence of any sexual assault," a police spokesman said, reiterating that there was also no evidence that it was racially motivated.

Several hundred mourners held a candlelight vigil in western Sydney on Wednesday night for the dead woman, who had been due to return home to India in April.

A spate of violent crimes against Indian students in Australia in 2010, including the stabbing to death of 21-year-old Nitin Garg as he walked to work at a fast-food restaurant in Melbourne, heightened tensions between Australia and India.

But since then the number of tourists visiting from India has picked up, and India's charismatic leader Narendra Modi spoke of warmer relations between the nations as "natural" during a 2014 visit.