At the height of his powers, former Billabong CEO Matthew Perrin was worth at least $50 million and was living the high life on the Gold Coast.

But his fall from grace was mighty.

A series of bad investments left him bankrupt in 2009. His wife turned on him, and now he has been sentenced to eight years in jail for fraud and forgery.

Here are the key points from his trial in Brisbane:

So, who is Matthew Perrin?

Perrin is a self-described "risk taker", lawyer, businessman and the main character in this case.

He was considered a brilliant law student at university, and met his ex-wife Nicole Bricknell through her bookmaker father when he was a young man.

Perrin's passion for the punt extended to his business ventures and made him very rich.

Nicole Bricknell says her ex-husband signed contracts behind her back. ( AAP: Dan Peled )

With friends and family, he pooled together $30 million to buy a 49 per cent share of Billabong in 1999.

A few years later, the company was floated and he and Ms Bricknell pocketed about $60 million. They built an $8 million home on the Gold Coast and had other property investments.

How did it go wrong?

Not all of Perrin's business dealings were successful.

Brisbane's District Court heard how a Chinese venture left him with tens of millions owing to creditors in Australia.

Several times he needed loans to prevent his assets from being repossessed.

In May 2008, Perrin urgently contacted the Commonwealth Bank to get $13.5 million in loans and credit extensions to prevent their family home being repossessed.

By March 2009, Perrin filed for bankruptcy and said he was having suicidal thoughts.

Why was he convicted for fraud and forgery?

In order to get that loan from the Commonwealth Bank, Perrin needed to mortgage the family home. However, the house was solely in Ms Bricknell's name.

Perrin openly admits he faked her signature on the documents and gave them to the bank.

This is where the legal troubles began.

The key questions in the trial were: Did his actions deceive the bank and cause them to give him money when they wouldn't have? And did he deceive his wife by signing her name?

Perrin said no to both, but the jury disagreed.

Perrin said for a decade his wife let him sign her signature on legal and finance documents. He thought he had the legal authority to do it, and said she was generally kept up to speed with their business and personal finances.

"We openly discussed that I could sign things on her behalf during our relationship," he told the court.

That's not what with she says.

Ms Bricknell said she didn't even know her home had been mortgaged until January 2009, when Perrin called an emergency family meeting.

"He never had any authority from me," she said.

"This man has taken from me and my children without my permission or knowledge."

Perrin's friends told the court Ms Bricknell knew about the failing investments and the mortgages.

As for the bank, Perrin said their staff knew he had given them dodgy signatures before, but that didn't stop them loaning him large sums of cash.

Did Perrin 'confess' to any crimes?

That depends who you ask.

He signed a six-page confession letter in which he admitted to going behind his wife's back for years and tricking the bank.

The letter was designed to absolve his wife of wrongdoing so she could save the house.

But in court, Perrin said he never wrote the letter and signed when he was mentally unstable and in a "dark place".

Perrin jailed for eight years

During the December trial, Perrin's defence turned on his wife.

"Nicole Bricknell has acted out of revenge and malice to see my client in jail," defence barrister Andrew Hoare said.

Prosecutor Glen Cash was equally scathing of Perrin, saying he avoided answering questions properly during cross-examination and had provided "utterly fanciful" evidence.

Mr Cash also tried to discredit the evidence given by the defence witnesses, including one who thought he saw Ms Bricknell reading loan documents at a coffee shop.

"He just seems to be a strange person who, for whatever reason, thinks he saw these things when in fact, he just did not," Mr Cash said.

After being found guilty, Perrin on Friday was ordered to serve a head sentence of eight years for fraud, as well as six years for forging a bank guarantee and seven years for forging his mortgage.

The terms will be served concurrently.

He will be eligible for parole after four years.