The first thing Deloitte executive Jeremy Cooper sees is the bloodied man in handcuffs lying face down on the footpath, surrounded by police.

Ten floors up, his colleagues at the Victorian headquarters of the international accounting giant press their faces against the heavily-glazed windows on the south side of the building. They gasp as shots are fired amid the trail of destruction on the footpath below.

A couple of blocks away, the firm's finance consultant Bhavita Patel is out to lunch with a couple of workmates. She doesn't come back.

Mr Cooper strides with purpose towards his office at 550 Bourke Street, a sleek modern tower of glass and concrete. Deloitte is the name at the top of the building. There are 2000 staff in this highrise; it is a microcosm of the city as a whole. 

Soon, the entire workforce will be traumatised, to some degree, by what has happened on their doorstep.

"It's still very raw and when you get reminded, it's tough," says Mr Cooper, the firm's Victorian managing partner. The Cambridge-educated Englishman speaks carefully and cautiously, as he must, but also with the gravity of leading his office through the months since the Bourke Street attack. 

On the frontline 

Bourke Street is blocked off, so Mr Cooper gets back to the building through the carpark in a side laneway off Little Collins Street. 

Inside, people are finding any spot they can near the windows with all eyes on the horrific view below. All along Bourke Street, office workers are in lockdown. There is not much else to do except wait and look.

The view from the Deloitte building, the scene of the Bourke Street attacks six months ago. Photo: Joe Armao

The car hits 33-year-old Bhavita at the west end of the Bourke Street mall, near the intersection of Elizabeth Street. Some of her colleagues see it happen. She succumbs to her injuries in hospital 10 days later.

Back at Deloitte, word spreads quickly that Bhavita has been badly hurt.

This is a powerful business that thrives on knowing what is happening. It does auditing, tax, consulting, among many other things.

It's still very raw and when you get reminded, it's tough

Deloitte Victorian managing partner Jeremy Cooper

But on this day, information travels by word of mouth, not by charts or numbers.

The life of the grid 

 Melbourne is a city of straight lines, a nest of skyscrapers bursting towards the sky at right angles from a criss-crossing pattern of streets.

It's pleasing to those who like order, where everything has its place. But organisation does not mean a lack of warmth.

The city's lifeblood is the people who fill the streets of Hoddle Grid. The crowd makes its way up to Spring Street, where the state's politicians debate the issues of the day, and down to Spencer Street, the first place many visitors see. Pumping away in the centre is Bourke Street, giving the rest life. Everyone in Melbourne travels this street. 

The public lay flowers at Bourke Street after five people died. Photo: Joe Armao

This is how it was on January 20, six months ago this week. Friday at lunchtime, school holidays, the tennis in full swing. Melbourne at its best. In five minutes of unexplained terror, all of that stops as a speeding burgundy Holden Commodore jolts through the city's heart.

Six die, not all of them straight away. Dozens escape with their lives but are stricken on the footpath, some critical. More than 1200 people contact the Justice Department's Victims Assistance Program over the next six months, seeking help. 

Thousands know someone who was there or someone who would have been, if they hadn't had that coffee after lunch. Millions realise their city has changed.

The inquiry begins 

Last Thursday, the first hearing for the coronial inquest into the deaths is held.

 The session is short, mainly administrative. It is decided the matter will be adjourned until the criminal investigation reaches its conclusion, however a brief opening statement has been prepared.

In plain, economical language suiting the polished interiors of Victoria's Coroners Court, the full horror is boiled down to a series of terrible paragraphs.

Counsel assisting the coroner, Mandy Fox QC, has the task of reading it out.

The first man to die, she says, is 25-year-old Japanese student Yosuke Kanno. It is the first time we have heard his name. He is killed on the footpath outside the Royal Arcade in the Bourke Street mall. Then comes Bhavita.

Further up Bourke Street, 22-year-old Sydney woman Jess Mudie is killed as the car hits her outside 405 Bourke Street. Matthew Si, 33, is next. He dies in hospital later that day.

After crossing Queen Street, the car barrels towards the Hakin family, 10-year-old Thalia with her mother Natalie and sister Maggie. Thalia is hit and perishes almost instantly.

Little Zachary Bryant, just three months old, is the final victim. He dies in hospital after being thrust from his pram at 501 Bourke Street. Around 450 metres separates the six deaths.  

The car finally comes to a stop past William Street after the fuel line to the engine fails. Police shoot the alleged driver twice, and they Taser him, too. He lies on the footpath and is taken into custody, as the city watches on. This is what Jeremy Cooper saw first. 

The alleged driver responsible for the Bourke Street tragedy. Photo: Leigh Henningham

Managing a traumatised office 

At Deloitte, counsellors are brought on site within a couple of hours to help provide support.

Regular emails are sent out over the next few days to provide updates on Bhavita's condition and senior managers make themselves available.

A makeshift shrine is set up at her desk, as everyone writes her little tributes, hoping she pulls through. She doesn't. Her devastated family make the heartbreaking decision to turn off Bhavita's life support.

"She loved working at Deloitte and she was a very loved colleague here, I think that helped them," says Mr Cooper.

Bhavita Patel was hit at the corner of Bourke and Elizabeth streets. Photo: Facebook

Mental health experts estimate one in five witnesses to the attack will have developed a mental health condition, such as post traumatic stress disorder, depression, an anxiety disorder or substance abuse problems.

For much of the Deloitte workforce, the wounds are yet to heal. That might never happen. The memories will probably come with them when the firm settles into its new headquarters at 477 Collins Street in a few years. 

"There are people who are still seeking professional help," he says. "Some are still quite severely impacted, they nearly died."