News Corp Australia says the homicide squad has compiled a list of more than 600 persons of interest based on police databases, social media and thousands of registration plates Ms Connelly's former long-time partner, Tony Melissovas, had kept a log of in the 18 months leading up to her murder.

The 40-year-old mother was a sex worker who was working from her Ford van in Greeves Street on the night she was killed on July 21, 2013.

Police will attempt to contact hundreds of men believed to be in St Kilda on the night of her death and have them give samples they can use to try and match with the evidence found in Ms Connelly's white van.

Police members from stations across Victoria are believed to be involved in the manhunt.

Ms Connelly had worked in St Kilda's red light district for at least a decade.

Her traumatised partner found her body in the van they lived in. The car had been parked in Greeves Street, across the road from St Kilda Gatehouse, a known safe haven for sex workers.

Homicide detectives cleared Mr Melissovas over her murder long ago.

The pair had been living in the van for about a month.

Police have been tight lipped about their three-year investigation.

Homicide Inspector Mick Hughes said on Sunday police still have significant work to do on the investigation into Ms Connelly's death.

"I want Tracy's family and friends as well as the broader community to know – the Homicide Squad is committed to bringing this investigation to a successful conclusion," he said.

A police spokeswoman would not confirm whether detectives had begun their doorknock.