More than 1,000 Victorian police workers have sought help from the force's support services since Melbourne's Bourke Street rampage, a top cop has revealed.

Six people died and many more were injured when a car was driven into pedestrians in the CBD mall last month.

Victoria Police's Assistant Commissioner Stephen Fontana said the effects of the tragedy were continuing to be felt across the force.

"We have had over 1,000 police members that have reached out for support," Assistant Commissioner Fontana said.

"This has had a significant impact on those members that attended the event on the night and have been involved in the investigation process.

"We have spoken to about 600 of those members [and] we will continue to make follow-up inquiries.

"This is because our employees, we are just normal people. Whilst we're trained and skilled to conduct the job, it does have an impact on us."

Assistant Commissioner Fontana said another 840 referrals had been made to a victim assistance program.

The accused driver, Dimitrious Gargasoulas, has been charged with five counts of murder, and Assistant Commissioner Fontana said he would face a sixth murder charge "in due course".

Facebook evidence prompts appeal for public help

Police have appealed for more help from an unknown person who provided information about the alleged driver.

Assistant Commissioner Fontana said police wanted to speak to the person who sent them a screenshot of Gargasoulas' Facebook page, which included details of his movements the day before the incident.

"We would like to talk to them, we think it's relevant to the case," he said.

Support services: Bourke St victims' support: 1800 819 817

Bourke St victims' support: 1800 819 817 Lifeline: 13 11 14

Lifeline: 13 11 14 Kids Helpline: 1800 55 1800

Kids Helpline: 1800 55 1800 SANE Australia: 1800 18 7263

After the attack, police urged the public to submit photos and videos via the force's social media accounts.

Assistant Commissioner Fontana said it was the first time police had done so.

He said more than 420 statements had since been taken from members of the community, emergency service workers and police.

"Some people are still struggling to come to terms with [the incident] and are not in a condition to provide statements," he said.

Thirty-seven people presented to hospitals after the incident.

Three of them remain in hospital and one is still in a critical condition.

Gargasoulas has been remanded in custody and ordered to face court via video link in August.