Mrs Baden-Clay's sister Vanessa Fowler muttered the word as her father, Geoff Dickie, spoke of ruing the day he gave permission for Gerard Baden-Clay to ask for his daughter's hand in marriage.

"You asked for my daughter's hand in marriage and I consented and gave my permission, but I didn't give you permission to betray her," Mr Dickie said, reading from his victim impact statement in Brisbane's Supreme Court after the jury's guilty verdict.

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"We accepted you into our family and you abused our trust with your lies and deceit ... Due to the mistreatment and subsequent murder of my beautiful daughter, I have failed in my duty as a father and I will have to live with that for the rest of my life."

Baden-Clay was found guilty of killing his wife at their home in the leafy western Brisbane suburb of Brookfield on April 19, 2012, and dumping her body on the banks of Kholo Creek at Anstead, about 14 kilometres away.

His trial heard he was embroiled in an affair with his long-time mistress Toni McHugh and was under significant financial pressure, owing hundreds of thousands of dollars to friends, family and ex-business partners at the time of his wife's disappearance.

Shaking violently, Baden-Clay stood with his eyes closed and his hands clasped tightly together, as the jury of seven men and five women delivered their verdict about 11.50am on Tuesday, after deliberating for nearly 22 hours.

The outcome marked a dramatic fall from grace for the former prestige Brisbane real estate agent, who prided himself on his lineage as the great-grandson of famed Scouts movement founder Lord Robert Baden-Powell.

The court's public gallery erupted in cheers, with Mrs Baden-Clay's family and friends yelling "yes", as the verdict was announced, concluding the 21-day trial.

Baden-Clay continued to shake and weep in the dock as his wife's family read their victim impact statements to the court.

"My sister, for the first time since she married you, has come out on top," Ms Fowler said, speaking to Baden-Clay. "Today, she is the hero, she is the one who has received justice."

The Baden-Clays' three young daughters were not present to hear their father be convicted of murder, but their grandparents, aunt and uncle spoke of their heartache.

"My heart breaks for the three precious girls who have been left behind," Ms Fowler said.

"They look for their mother, cry for their mother, they miss their mother, they love their mother … When I have a little girl snuggle up to me and say 'Aunty Ness, I miss mummy', I feel great sadness, my heart sinks and I am even more determined to make their lives happy and full of love, just as Allison would have wanted."

Mrs Baden-Clay's mother, Priscilla Dickie, struggled to contain her grief as she spoke of the three granddaughters she had "wholeheartedly" taken into her care.

"They miss her terribly and cry for her at night," she said. "To have mummy put them to bed one night and then to wake up the next morning and be told that mummy is missing, what a situation to face.

"What can you do or say when dealing with the stress of hugging a little crying girl saying 'I want my mummy', or answering the question 'does mummy love me?'

"The girls will never see their mother again … they have been condemned to a life sentence without the love and companionship only a mother can give."

A kayaker found Mrs Baden-Clay's decomposing body on the muddy banks of Kholo Creek on April 30, 2012 – 10 days after her husband reported her missing.

Mrs Baden-Clay's family spent every waking hour at the police command centre, set up at Brookfield Showground, during the search.

Baden-Clay made only one appearance at the command post, telling police on his arrival that he was feeling "shithouse".

Forensic pathologists could not determine the cause of her death, but prosecutors suggested Baden-Clay smothered his wife to death while their daughters slept soundly in their beds.

Most incriminating in the circumstantial case against the father of three were three scratches on his right cheek.

Baden-Clay dismissed the injuries as shaving cuts, but four forensic experts told the court the abrasions were more consistent with fingernail scratches.

"Because of her life experiences, we had the utmost faith in Allison's ability to handle any situation in her life," Mrs Dickie told the court. "This she proved while for, for her life, leaving those telling marks on Gerard's face on that fateful night. God bless her.

"It was obvious to me that one of the last things Allison did was to leave her marks on her husband."

Leaves from six different species of plants found entwined in Mrs Baden-Clay's hair and clothing matched six species of plants found growing around the Baden-Clays' Brookfield Road home.

Only two of the same species were found in the area around Kholo Creek. Crown prosecutor Todd Fuller, QC, said Baden-Clay was confronted with a potentially "catastrophic convergence of events" on the night he killed his wife of 15 years.

His mistress, Ms McHugh, was due to come face-to-face for the first time with Mrs Baden-Clay at a real estate conference the following day and Baden-Clay risked having his "double life" exposed at the impending run-in.

The 43-year-old vehemently denied the accusations, even stepping into the witness box on the 11th day of the trial to profess his innocence.

He pointed to his wife's history with depression to suggest she took her own life in the early hours of April 20, 2012. He also suggested she may have died by misadventure or accident, when she stepped out in the early hours of the morning to "clear her head" as a result of the adverse effects of her antidepressant medication Zoloft.

Justice John Byrne was scathing of Baden-Clay as he sentenced the 43-year-old to life behind bars.

"The killing was not premeditated, but it was violent," he said.

He said Baden-Clay had used a razor blade to disguise what were really the marks of Allison's fingernails on his face.

He also said he had invented the idea of a drug overdose as a ruse about what had really happened to and had shown a profound absence of remorse for his crime.

"You have no criminal history, but you are definitely not of good character," Justice Byrne said.

"You are given to lies and public deception, so much so that whatever you may say on any application for parole, 15 years or more hence, will need to be assessed with considerable scepticism.

"The community, acting through the court, denounces your lethal violence."

Baden-Clay will serve a minimum of 15 years behind bars under Queensland law.

Outside the courthouse, Mrs Baden-Clay's friends and relatives released yellow balloons in the air, in memory of her favourite colour. They shouted "for Ally" as the balloons rose against the backdrop of a bright blue sky.

Detective Superintendent Mark Ainsworth, who oversaw the police investigation, said the conviction of Baden-Clay was a long time coming.

"We never got to meet Allison, but dealing with the Dickie family and extended family, after this lengthy investigation, I'm sure I not only speak for myself but the other investigators, I feel we know her," he said.

"We should all agree that Allison was nothing short of a wonderful person, a wonderful mother, friend and daughter.

"It's now up to the Dickies to look after these three wonderful children. And I'm sure none of us would like our children to go through what they're going through at the present time."