A man who killed four members of the same family in a house fire in Co Fermanagh was described as having a “dangerous and disturbing part of his make-up” as he was sentenced to 29 years in prison.

Daniel Sebastian Allen, 33, previously pleaded guilty to the manslaughter of his partner Denise Gossett and the murder of her daughter Sabrina Gossett, 19, son Roman Gossett, 16, and Sabrina Gossett’s 15-month-old daughter Morgana Quinn in the deliberate fire at a house in Derrylin, Co Fermanagh, on February 27 2018.

On the death of 45-year-old Denise Gossett, Allen previously admitted manslaughter by reason of suicide pact.

Allen, whose address was given as HMP Maghaberry, also admitted arson with intent to endanger life.

He appeared in the dock at Belfast Crown Court on Wednesday for sentencing.

Mr Justice O’Hara said Allen came from an “unstable, unhappy background”, and “lived most of his life online … in a fantasy world” because of isolation from others.

But the judge said the killings required planning, and could not be explained by a “sudden detachment from reality or loss of control”.

“There is a very dangerous and disturbing part of his make-up that led to these murders,” he added.

Mr Justice O’Hara said Allen would serve 29 years in prison before he could be considered for release.

Taking into account time already served, the judge said Allen would not be eligible for parole until 2047.

Denise Gossett’s surviving daughter Samantha said her life would never be the same again.

A statement from Ms Gossett was read outside court by Detective Inspector Hazel Miller.

“My beautiful mother was taken from me. My younger brother and sister, Roman and Sabrina, along with Sabrina’s wee baby Morgana are all gone too,” she said.

“Their four lives were taken in a fire started deliberately. And it breaks my heart to think on what happened; to think on how they died.

“I miss them so much. And, to be honest, it’s very difficult to convey such a loss in words. My remaining family and I are incredibly thankful for everything the police, and those who helped bring this to court, have done.

“It is hard to move on with our lives, and my life will never be the same again. But the support of everyone, especially my partner and friends, has truly meant such a lot.”

Ms Miller said Allen had been held accountable for his actions.

“Three generations – a mother, her two children and her granddaughter – perished in a fire deliberately started by Daniel Allen in their home in Derrylin,” she said.

“This was a horrific and cruel act. It’s hard to even begin to imagine the panic, fear and sheer suffering. With the use of forensic evidence, and working in partnership with the Public Prosecution Service, Daniel Allen has today been held accountable for his actions.

“I’m deeply mindful, however, that this is an event that will never be forgotten. We’ve seen destruction and a loss beyond words. My thoughts are with the remaining family members, whose lives won’t ever be the same.”

The head of the Serious Crime Unit at Northern Ireland’s Public Prosecution Service Ciaran McQuillan said Allen’s “cruel behaviour was impossible to comprehend”.

“Daniel Allen has been sentenced to one of the longest tariffs in prison imposed by the courts in recent years for killing three generations of one family, including two teenagers and a toddler,” he said.

“He callously took the lives of those close to him for reasons that may never be fully understood. His actions were grotesque and shocking and have inflicted terrible suffering on his victims’ surviving family and the wider community that they will have to carry for many years to come.

“The Police Service of Northern Ireland carried out a painstaking investigation into this case. The prosecution team in the PPS’s Serious Crime Unit worked closely with them in what was a complex and multi-jurisdictional case to help build a robust court case against Allen.

“The scenes encountered by police, other emergency services and members of the community who tried to help Denise and her family were truly harrowing. We thank every witness who was prepared to assist in the event of a trial.

“Whilst Allen’s guilty pleas have saved the victims’ family the ordeal of a trial, we hope the conclusion of this prosecution can bring some small sense of closure to all involved.”