A wolf in sheep's clothing: Simon Gittany threw his girlfriend from a 15th floor balcony.

Joshua Rathmell thought he saw a garbage bag thrown from the fifteenth floor of a CBD apartment building.

Or perhaps it was luggage.

He couldn’t be sure. He wasn’t close enough. Rathmell was walking to the ABC offices where he worked, and passing through Sydney’s Hyde Park.

It was just before 10am on a Saturday morning in July 2011.

Liverpool Street, usually littered with impatient commuters and honking buses, was quiet. Locals sat outside a cafe called The Canopy, facing Hyde Park, a welcome splash of green in the middle of a congested business district.

For the nearby residents sitting at that cafe, they would see something very different.

It wasn’t a garbage bag thrown from The Hyde, the apartment building behind them.

It was a body. And it belonged to 30-year-old Lisa Harnum.

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Whoever threw that luggage, according to Joshua, looked like a "junkie".

He was agitated. He wasn't wearing a t-shirt. It was enough to catch the passersby attention.

According to Amy Dale's award-winning book, The Fall, that man wouldn't appear on the street below for some minutes.

By the time he did, Lisa was surrounded by people who had seen the moment of impact. A man named Dr Angus Grey had raced out of his car to help. He checked for signs of life, noticing that the woman - who couldn't have weighed more than 50 kilos - had at least a broken leg, broken ribs and a broken back. She wasn't breathing. There was no pulse.

That's when Lisa's fiance, 40-year-old Simon Gittany, emerged on the scene.

"Come back, baby, come back," he said, his tone both forced and oddly calm.

Simon was the agitated "junkie" Joshua had seen just moments before.

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Simon told police Lisa had "walked out onto the balcony"of their shared apartment and climbed over the rail. He said he asked, "What are you doing?" and "tried to grab her" but it was too late. Lisa had jumped.

What unfolded was a two year investigation, where many of Simon's claims would fail to add up.

If Lisa had jumped, why was she still wearing her bag?

Why could neighbours hear screams in the seconds leading up to the fall?

Why did Simon take so long to come downstairs?

Why did the footage of Simon travelling down in the lift depict a man high on adrenaline, pacing and waving his fists?

The biggest question for Simon's defence was one impossible to answer: If Lisa had thrown herself off their balcony, why weren't her finger prints on the ledge?

Forensic evidence indicated that Lisa had never come in contact with the glass that lay between their balcony and the drop to the bottom. It was as though someone else had thrown her from it.

As the court case unfolded, the history of Simon and Lisa's relationship was put on full display.

Simon had always been controlling and jealous.

Listen to True Crime Conversations, where we speak to journalist and author Amy Dale about the murder of Lisa Harnum. Post continues below. 

Their relationship, which had been put on fast forward by Simon almost immediately, relied on him dictating every moment of Lisa's life - from where she was going to what she wore.

Text messages found that Simon told Lisa not to look in the direction of other men, wear revealing clothing or high heels, wear her hair out, leave their apartment without permission or confess anything to a priest.

When Lisa told him she felt as though she had no friends, he called her "cute".

One text read: ''Who the f*ck do you think you are walking around the house like you own it or coming and going without my permission?… You walk around like a peacock with your hair out.''