Mohinder Singh seemed confused and talked about "the war" before he crashed a 19-tonne delivery truck on the Eastern Freeway on April 22, 2020.

Night shift supervisor Stephen Harrison text Connect Logistics boss Simiona Tuteru saying: "I am concerned about his (Singh's) mental state".

"I don't think he should be driving. I told him to go to (the) doctors straight away," the text also said in documents released by Melbourne Magistrates Court on Tuesday.

Tuteru, who is charged with 82 offences including four of manslaughter, replied: "Will speak to him".

The 49-year-old is charged with multiple breaches of heavy vehicle regulations, including directing or requiring to work while fatigued.

Other charges include obtaining financial advantage by deception for time sheets submitted in a false name to hide the real number of hours worked.

Mr Harrison told the court he thought Singh was fit to drive during the night shift before the crash, adding there was nothing to indicate he was on drugs.

Singh spoke about problems with his marriage and "didn't look tired and looked not frustrated but confused".

"He said to me that he could remember a date from the war ... It's the only thing I thought 'oh, that's a bit strange'," Mr Harrison said.

"My advice was to go and seek medical advice ASAP ... go and see a doctor."

He didn't, and later crashed a 19-tonne semi-trailer into Senior Constable Lynette Taylor, Senior Constable Kevin King, and constables Glen Humphris and Josh Prestney, in the freeway emergency lane.

Singh was high on ice and severely sleep deprived, and had spoken about seeing witches, ghosts and aliens, including to his wife and children.

He was last month jailed for a maximum of 22 years after pleading guilty to charges including culpable driving causing death.

Another driver who worked with Singh said employees were required to sign a form before each shift confirming they weren't drug or alcohol affected.

But the driver, Adrian Thorne, also said the only time he was drug tested was after the fatal crash.

One of Singh's associates told the court he would pick her up in his truck and they'd use ice together.

The woman, Bonnie Wilson-Knight, spoke about accompanying Singh as he delivered chicken to KFC and hiding in the truck so she wouldn't be found out.

The committal, to determine if there's enough evidence for Tuteru to stand trial, is due to continue on Wednesday.

Australian Associated Press