The employee of a Shepparton tyre business who was tested for COVID-19 has led DHHS to uncover the person who caused the Kilmore cluster did not disclose their travel to Shepparton.
Goulburn Valley Health and DHHS tested 12 people at the Central Tyre Service after a worker received a positive test result on Tuesday.
Through interviewing that worker, it was determined a truck driver who travelled to Kilmore and Benalla did not tell contact tracers originally that they also went to Shepparton on September 30.
"This matter has been referred to Victoria Police," Victorian Premier Daniel Andrews said.
"Information has been referred to the DHHS compliance team. Victoria Police will do whatever they think is appropriate in this case.
"There's infections in Shepparton today that we know of ... that were all completely preventable if this individual had told the full story.
"It's only when you don't that we all have problems."
Mr Andrews said people shouldn't be fearful of coming forward to be tested.
"But you've got to tell us the full story," he said.
"He did have a permit ... the key point, though, is things have then happened, places have been visited, that are not allowed."
The truck driver, who infected people in Kilmore after dining at a cafe when he was restricted to takeaway-only, also visited Bunnings in Shepparton on September 30.
Chief Health Officer Brett Sutton was asked if he was confident DHHS and GVH had the full timeline of the supplier's travel on September 30.
"We'll look into that today," he said.
"This will be a power of work today, investigating all details."
Hundreds of people have attended for testing at Goulburn Valley pop-up clinics.
Bunnings regional operations manager Tony Manzone said in a statement staff and customers were wearing face masks at the time of the visit on September 30, which reduces any risk of spread.
"The store has undergone 14 deep cleans using disinfectants since the visit as well as the routine cleaning that occurs throughout each day," he said.
Victoria's head of the COVID-19 contract tracing response within DHHS, Jeroen Weimar, has confirmed a link between the Kilmore cluster and the Shepparton cluster.
He told 3AW's Neil Mitchell DHHS was't told by the supplier who visited Kilmore and Benalla that they also went to Shepparton, until positive cases were picked up yesterday.
"What appears to have happened is the individual who had a permit to travel into regional Victoria, as well as stopping off in Kilmore also stopped off in Shepparton," Mr Weimar said.
"That information unfortunately wasn't forthcoming until last night.
"The three cases in Shepparton were discovered yesterday afternoon.
"Somebody came forward, somebody did the right thing in Shepparton and they were symptomatic over the weekend.
"We got her positive result early yesterday afternoon.
"The warnings go back to the 30thof September because whilst talking to the lady who tested positive, we tested the 11 to 12 people in her workplace.
"Three in total are positive. In talking to the three positive cases yesterday afternoon, what became apparent was that the index case was somebody who came out of Melbourne, who travelled through Kilmore ... and visited Shepparton on the 30thof September.
"Something clearly happened on the 30th of September between that individual and the people in the tyre shop, which meant the virus was able to spread."
He said the case in Shepparton on October 5 that turned out to be a false positive was not linked.
The supplier contracted the virus from the Chadstone outbreak and had not been tested when they travelled to regional Victoria.
"They then quite rightly were permitted to travel into regional Victoria, they went to Kilmore, Benalla and Shepparton," he said.
"We know about Kilmore, we know about Benalla, we didn't know about Shepparton."
"We're only as good as the information we get.
"It is very hard for me to identify where someone's been if that information is not forthcoming."
Nobody in Benalla has tested positive as a result.
Earlier that day, the contractor dined in a Kilmore cafe when they were meant to be getting takeaway only, which caused five people to contract the virus.
Mr Weimar was asked why contact tracers didn't better quiz the supplier or his employer on where he travelled.
"That's all part of the conversations we've had with the individual," he said.
"I don't know if that individual was a sole trader."
IN OTHER NEWS:
Three people who work at the Shepparton tyre business the supplier visited tested positive.
As a result, numerous businesses have been closed for a deep clean and staff are isolating.
A pop-up testing site has been established in the city.
Exposure sites: https://www.dhhs.vic.gov.au/case-locations-and-outbreaks