Inside Portmoresbey Cecil’s murder of mother-in-law Sue Duffy

His weapon was a hunting knife – by name and purpose. “BJ” Cecil was hellbent on finding his former wife and teaching her a lesson. When her brave mother stepped in, she paid the ultimate price. SPECIAL REPORT.

A dormant killer had been part of wife’s family for 15 years before he brutally stabbed her mother to death with a hunting knife.

Debbie Duffy met Portmoresbey Cecil when she was 18 and together they had a son in 2010 and had a six-year-marriage.

Fast forward to 2024 however, the marriage had ended, Cecil was angered by not knowing where Debbie was and, “fuelled by hate and his need for control” which “outweighed the importance” of her mother’s life, he repeatedly plunged his knife into her body.

This is what Debbie told Queensland’s top judge, Justice Helen Bowskill, during the sentencing of Cecil for murder after a four-day trial in the Supreme Court in Rockhampton this week.

It only took 30 minutes for the jury to find Cecil intentionally killed 71-year-old Susan Margaret Duffy on August 21, 2022, just after 3pm.

Sue Duffy.

Horrific photographs shown in court of the sickening injuries inflicted on her 63kg body revealed Mrs Duffy’s violent death was the stuff of nightmares.

Cecil’s confession he purchased a hunting knife that day but claimed he was “just going to intimidate Debbie” by “showing it to her” – was a flag his rage was fuelling DV tendencies.

Debbie, who after leaving Cecil in March 2022, was running her own hair salon in Denham Street and working as a boarding house supervisor at Rockhampton Girls Grammar, found her mother’s fatally wounded body in the lounge room of her Allenstown family home. She told the court she now battled with post-traumatic stress disorder as a result of that day and “also from the physical, emotional and mental domestic violence from the one responsible for her murder”.

“Your Honor, please understand my perspective for when I say how extremely fortunate I am to be standing today – it’s an unfortunate reality,” Debbie said.

“My life was spared by chance. Mum suffered a brutal death. I often think about how terrified she was.”

Sue Duffy with her daughter Debbie.

“My son and I have lived in hell on earth since that day,” she said.

“We have lived through extreme emotional pain, grief and suffering that is ongoing.

“We have faced mental health issues, judgment, loss of privacy, financial hardship, rumours and breakdown in family connections and massive life changes.

“I was left with fires to put out after already walked through hell.

“Our mortgage repayments and rates, his (Cecil) phone bills and unpaid fines and toll notices, just to name a few.

“All while we were trying to grieve the loss of our mother.

“I’ve had to live in fight mode since that day and I’m burnt out.

“I had to change my career, which requires me to travel away from my son regularly in order to keep a roof over our heads.”

‘You didn’t call anybody – you just left’: The murder

From the first interaction Cecil had with Mrs Duffy when he arrived at West Street his behaviour was irrational.

Mrs Duffy spoke to Cecil about the breakdown of his marriage and the arguments he was having with Debbie.

Portmoresbey "BJ" Cecil.

Justice Bowskill said Cecil said or did something that caused Mrs Duffy to become concerned and told him she was calling the police.

“This is a person she’d never been in an altercation with, never had a harsh word to say to you, so something that you did in that moment made her so concerned she said she was going to call the police,” she said to Cecil.

“Your response to that, a young man of 35, solid built man, was to punch her in the face with such force that she fell to the ground crying.

“You did nothing to help her in that situation. You left. You didn’t check if she was all right.

“You didn’t call anybody. You didn’t say to someone ‘I’m out of control. I’ve got to get out of here. Can you help me?’ You just left.”

Justice Bowskill said it was unsurprising Mrs Duffy would stand up, throw something at Cecil and say “how dare you hit me” after he returned unannounced.

She said Cecil’s claim Mrs Duffy attacked him “lacks credibility and is implausible”.

“What happened next, as we know, was a ferocious, violent stabbing of this 71-year-old woman with a hunting knife you say you had purchased earlier that day,” Justice Bowskill said.

Dan Duffy says he was dazzled when he first met his future wife Sue in Sydney in the late 1970s.

“I’ve never understood this man even though I tried for nearly 15 years,” Debbie said.

“Seeing him locked up doesn’t bring Mum back.

“He gets to breathe but she doesn’t.”

‘The trauma you cause is ongoing and your existence is traumatic’

The horrific death of a beloved mother wife and grandma has left a family with intense and overwhelming emotions of grief, heartbreak and anger for the woman who was kind to most people and even still greeted Cecil with a hug and a kiss on the cheek right up until the day before her murder.

Sue Duffy with her daughter Debbie, husband Dan and son Gavin.

Debbie said she still had questions about why someone would murder her mother.

“Her love for me was unconditional and our bond was unbreakable,” Debbie said.

“She taught me how to love deeply and how to show compassion for people in their situations.

“Mum was my mentor, universal teacher and my spiritual healer.

“Mum would always remind me to look at the positive in all situations and reminded me to do what makes me happy.

“That’s all she’s ever wanted for anyone.

“Mum sacrificed everything for me. I’ll forever cherish her and continue her legacy to be happy and make her proud.

“That was what I wrote for my mum’s funeral.

Sue Duffy pictured holding one of her grandchildren.

“Mum treated friends of mine and Gavin’s as her own, including our partners.

“Mum expressed her love for us in every moment but especially on Christmas and birthdays.

“Mum is no longer here to help support our son like she always did.

“He no longer has his Nanna, no longer has his father.

“All the things he (Cecil) didn’t think or care about that day has affected us forever.

“Mum’s death has affected so many people both inside and outside our community, our family, friends and complete strangers.

“My dad no longer has his favourite person, the love of his life.

Sue Duffy, pictured with her husband Dan.

“They were meant to be enjoying the start of Mum’s retirement together.

“Her absence is paramount in dad’s life.

“Seeing his sorrow for his wife, because someone I loved, is excruciating.

Sue Duffy, pictured with her husband Dan.

“My brother lost his mother. I understand the extreme grief of her absence in his life.

“My niece and son no longer have their Nanna to share their life with.

“My son was the centre of his Nanna’s world. He adored her.

“Mum always greeted you with a big grin, a hug and a kiss on the cheek.

“Mum and dad dropped you off a birthday to our house just a few weeks before.

“Mum was always there to support you and I and would do anything for our son.

“My mum was a peacekeeper.

“You should understand the pain we feel because our son and I lived that pain with you when you lost your father.

“Your family has suffered enough.

“Our son adored you.

“Your son has suffered the most. Not only has he lost the two closest people in his world, but he also now has to live with your actions and consequences on his name.

“The trauma you cause is ongoing and your existence is traumatic.”

Debbie’s brother Gavin said that despite Cecil’s absence, his son would grow up to achieve success: “Serving as a living testament to the resilience and love that our mother Susan Duffy instilled in him.

Sue Duffy, pictured with her husband Dan, was murdered by her former son-in-law Portmoresbey Cecil on August 21, 2022. He stabbed her in her West Street, Allenstown home, causing 15 sharp force injuries – three of which were fatal type.

“Her enduring guidance and unwavering support will continue to shape his future, providing him with the strength, determination and values necessary to navigate life’s challenges, and adversities; despite the immeasurable loss caused by your actions.”

“The intensity of the emotions stemming from this heinous act is overwhelming, leaving behind tears of profound sorrow and tears of absolute seething anger.

Reading his victim impact statement to the court, Gavin said his mother, was “a beacon of strength and guidance”.

“Her absence now leaving an irreplicable void in our lives.

“All that remains are shattered dreams, at times, turning into haunting nightmares of that fatal afternoon.

“The profound impact of her absences reverberating through the lives of many, causing untold pain and suffering.

Daniel Duffy and his daughter's best friend of 20 years Kasey Mitchell leaving Rockhampton courthouse this week.

“The absence of any remorse from the perpetrator has only added to the burden that we carry.

“Despite these challenges, we find solace in the enduring strength of the Duffy psyche, and the unwavering support of those around us.

“We refuse to be broken by the silence and ongoing thoughts of the perpetrator.

“The celebration of my mother’s life will endure everlasting testament to a beautiful legacy she has left behind.

“Her memory will forever be cherished, her spirit continuing to inspire and guide us through the darkest of times.

“In addition to the profound impact on our lives, my father has been robbed the opportunity to share so many more cherished moments with his beloved wife Susan.

“He has lost the chance to complete their fairytale life together – a life that they dreamt of and worked towards for so many years.

“The impact of this tragic loss has been immeasurable, affecting his well being in ways words cannot fully express.

Cecil has been sentenced to life in jail.

Originally published as Inside Portmoresbey Cecil’s murder of mother-in-law Sue Duffy