The 55-year-old Yorta Yorta woman was placed in a Castlemaine cell after being arrested for drunkenness on a train on December 5, 2017. She died two weeks later.

"I am deeply sorry for your loss and deeply sorry for our disrespectful care and the treatment Tanya received that day," Ambulance Victoria clinical operations director Michael Stephenson said to Ms Day's family during an inquest on Tuesday.

"It was a dark moment for our organisation," he later said. "I'm sorry."

Members of Ms Day's family thanked Mr Stephenson for his courtroom apology.

Police officers did not see Ms Day fall. They entered the cell more than three hours later at 8.03pm, when they noticed a bruise on her forehead and called an ambulance.

The first paramedic on the scene was Lisa Harrup, who said she was told by a police officer that he saw Ms Day slip from a seated position.

"All of my treatment was based on what I thought was an accurate history provided by a police officer. Why wouldn't he know exactly what had happened?" she told the inquest last week.

But Mr Stephenson has contradicted the paramedic's version of events, saying it was clear the woman had a traumatic injury and was paralysed at some points.

"She's got a haematoma on her forehead - by definition she has a traumatic head injury," Mr Stephenson told the court.

"The bruise came from trauma so it has to be traumatic."

He said it didn't appear Ms Day moved her right arm or hand on CCTV of the cell, disputing Ms Harrup's evidence that she did.

"I don't think it did happen," he said.

"Tanya looks to be paralysed from her right-hand side."

Tuesday's evidence in Melbourne coincided with a rally that marched from state parliament to the Coroners Court to show support for Ms Day and her family.

The inquest continues.

Australian Associated Press