The state's hotel quarantine inquiry on Tuesday was shown WhatsApp messages exchanged by Department of Jobs, Precincts and Regions bureaucrats on the evening of March 27.

"Gotta be careful with a lot of security companies. Heaps of cash work," one warned.

"Cowboy industry," another said.

"Needs to be reputable. Don't want (redacted) rogue (redacted) prowling the corridors," another replied.

It's since been revealed infection control breaches by security guards, many of whom were subcontracted, led to the state's second wave of COVID-19.

About 99 per cent of the state's second wave can be traced back to outbreaks at two hotels - the Rydges on Swanston and Stamford Plaza.

Jobs department secretary Simon Phemister said his staff were tasked with hiring security companies following a meeting at the state control centre on March 27.

He wasn't present at the meeting but knew it was attended by high-ranking Victoria Police officers as well as Emergency Management Commissioner Andrew Crisp.

"I don't know who made the decision," Mr Phemister said.

"All I know is that we were commissioned to procure private security in that 4.30pm meeting."

He said if the decision had been made earlier, as other witnesses at the inquiry have claimed, he would have already started contacting firms.

"I'm certain I wouldn't have waited hours," Mr Phemister told the inquiry.

According to recordings of the meeting, Victoria Police Assistant Commissioner Mick Grainger told Mr Crisp it was the force's preference that private security be the "first line of security".

Mr Phemister said his department was looking for companies with a ready supply of personal protective equipment, experience working with the government and the ability to "scale up" as more travellers returned home.

MSS Security, Unified Security and Wilson Security were awarded contracts within hours.

All three companies subcontracted others to provide guards for the program.

The inquiry heard Unified Security took on the bulk of the work, placing 1754 guards, mostly subcontracted, across 13 quarantine hotels at a cost of about $30 million.

They were not on the government's preferred contractors list and charged higher hourly rates than MSS and Wilson for the same work.

Mr Phemister and his team were not aware the government had a preferred contractors list.

In a written submission to the inquiry, Mr Phemister said he did not consider the possibility of subcontracting.

Department of Health and Human Services secretary Kym Peake also appeared before the inquiry.

While her department was referred to as the control agency of the program, she denied it meant they had "sole accountability".

Ms Peake said the jobs department managed hotels, security, food, cleaning and the guest helpline, while the health department was responsible for health and wellbeing.

She said her department had not been consulted about the use or suitability of private security guards.

After almost two months of public hearings, no witness has been able to say who is responsible for the decision.

"Isn't there a problem with that model when it comes to these important decisions that we're unable to ascribe back to any particular individual or department?" counsel assisting the inquiry Ben Ihle asked.

"I know it would be more straightforward if there was an ability today to say there's a single accountability ... but I do think the whole weight of the evolution of public service delivery is that people are not carved up into portfolios," she said.

Ms Peake will continue giving evidence on Wednesday, when Jobs Minister Martin Pakula and Emergency Services Minister Lisa Neville are also due appear.

Health Minister Jenny Mikakos and Premier Daniel Andrews have been pushed back to Thursday and Friday respectively due to scheduling issues.

Australian Associated Press