How killer who murdered gran, 94, after game of truth or dare was nailed thanks to Tunnock’s tea cakes found at scene
A GAME of truth or dare and a pile of discarded Tunnocks tea cake wrappers were the bizarre clues that helped nail a student who murdered his 94-year-old gran in a house blaze.
Tiernan Darnton, 23, almost got away with killing Mary Gregory after fire chiefs concluded a dropped cigarette had sparked the fatal inferno and an inquest ruled her death accidental.
But the truth finally came out after Darnton bragged to pals during a game of confessions that he had killed his step-gran in 2018 — a claim they did not believe at the time.
The following year, he told a counsellor about the admission, insisting there was someone “who could send me to prison ’cos of what he knows”.
The therapist alerted cops.
It was only when the case was reopened by police in 2019, and photos of evidence — including biscuit wrappers in the bin — were revisited, that the shocking truth emerged.
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Heartless Darnton had started the fire at Mary’s bungalow in Heysham, Lancs.
Three years later he was finally brought to justice — despite telling detectives in interviews he had made a false confession due to “misplaced guilt”.
Mary’s carer Karolina Madejska — who was the last person to see her alive — will now feature in a new Channel 5 documentary, The Murder Of Mary Gregory.
And the 27-year-old, from Morecambe, Lancs, today speaks publicly for the first time about how she helped police crack the case and put Darnton — who it is thought may have autism and depression — behind bars for at least 15 years.
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The mum of one, who gave evidence for the prosecution, says of the monster: “If the police hadn’t reopened the case, he could still be walking the streets doing God knows what. He could have done it again.”
During Darnton’s trial in 2021, Preston Crown Court heard how the serial killer-obsessed fiend had drawn up a “kill list” of other people.
Karolina, who began caring for Mary in 2017, says: “When I met him, I thought he was a sweet, polite guy.
“I thought he was just a normal teenage boy. Never in a million years would I think he could be a killer.
“Thinking about it now gives me goosebumps.”
The documentary, which airs on Wednesday, tells how Darnton was a loner at school who owned a pristine SS uniform and ornate dagger.
A former student at Kendal College and Lancaster & Morecambe College, he lived with step-father Chris Gregory, who later home-schooled him. But he was regularly at Mary’s home.
Karolina says: “He would often be there two or three times a week. He was always there on Friday nights.”
She admits she never questioned why Darnton was not out with friends, like most lads his age, adding: “I just thought he wanted to see his grandma.”
But the killer’s motive for being in the property was clearly more sinister, as police later found a plan of Mary’s home — part of his meticulous murder plot.
He had written “good hiding place” and “quick exit”, as well as making references to needing a “good alibi”.
Karolina, who visited the elderly woman three times a day, reveals that Mary became increasingly upset by Darnton’s presence.
She says: “She always used to say, ‘The boy, he’s helped himself to my food and made a mess. He’s always helping himself’. She was upset because she liked to have a nice, clean kitchen.
"We would try to help her clean it up.
“When carers arrived and saw a mess, we knew that Darnton had been in the house.”
When Karolina visited on the evening of the fire, Mary and her grandson were embroiled in a row.
She recalls: “Mary was in the conservatory and Darnton was in the living room. Mary was really angry.
“He came in and they were having an argument in front of me — I can’t remember what it was about.
“I was trying to calm her down and made her a cup of tea.”
It was the last time Karolina would see Mary alive.
Darnton went to the elderly woman’s home in the early hours and started a blaze in one of the bedrooms by setting fire to a curtain with a lighter.
A neighbour recalls in the documentary how she woke to hear Mary hammering on the walls.
Firefighters found the OAP in the conservatory, where the exit had been blocked.
She had suffered such severe smoke inhalation that the inside of her mouth was black, and she died in hospital four days later.
Karolina, originally from Poland, initially blamed herself for the blaze.
She says: “I was thinking, ‘What if I had left the cooker on?’
"But the police told me it had nothing to do with me. I was relieved, but so sad.”
Officers from other forces were drafted in to help with the two-year probe into Mary’s death, known as Operation Ellsworth.
If the police hadn’t reopened the case, Darnton could still be walking the streets doing God knows what. He could have done it again.
Karolina Madejska
Speaking in the documentary, senior investigating officer Detective Chief Inspector Zoe Russo said: “The investigation was complex.
"Traditionally, we would rely on CCTV, phone evidence, witness evidence. Some of that was no longer available.”
There was also no crime scene, as Mary’s house had been renovated and sold after the fire.
What the police did have, though, was Darnton’s phone and laptop, seized during his arrest.
They found that a month before the fire, Darnton — who was 17 at the time — had searched for “under 18 killing”. He also looked up “I’m a murderer”, “feeling guilty for murder” and “urge to kill again”, plus “I want to cause evil”.
But DCI Russo tells film-makers the evidence was “circumstantial” and “did not prove he was responsible for Mary’s death”.
Undeterred, police painstakingly analysed photographs taken by crime scene investigators after the fire.
Detective Inspector Jo Dent tells the programme: “We had to go through the photographs looking for anything that could be a clue as to what had gone on that night.”
Pictures showed an open lock box with a key missing, the wire to Mary’s landline unplugged and a smoke alarm disabled.
Karolina says she also told police that Mary never smoked in the bedroom, where the fire started.
But it was a photo of a plastic bag containing a can of Coke and Tunnock’s tea cake wrappers at the top of the kitchen bin that would eventually provide a 2020 breakthrough.
Karolina says: “I told the police that Mary wouldn’t eat Tunnock’s tea cakes and she never liked Coca-Cola. She would rather have a cup of tea.”
The bag was from a local garage, where a computerised search of sales put Darnton — who at one point claimed his actions were a mercy killing due to Mary’s dementia — at the scene around the time of the fire.
It was the final piece of the jigsaw which allowed cops to charge him.
A jury later convicted him of murder.
Karolina says: “I can’t understand what was going through his head. He said he tried to put her out of her misery but he put her through more pain with the fire.
"For him to admit it, I don’t know if he was trying to show off, or maybe he was proud.”
She also talks of her heartbreak at losing Mary and how the murder has caused a rift in the family.
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And she adds: “Nothing was wrong with her. She had dementia but she was happy and healthy. It didn’t give him any right to do what he did.”
- Truth Or Dare: The Murder Of Mary Gregory is on Channel 5, on Wednesday, at 10pm, and available to stream on My5.
