Jordan Monaghan, 30, killed three-week-old Ruby as she slept in her Moses basket at home in Blackburn, Lancashire, in 2013.

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Eight months later, the monster also smothered his 21-month-old son Logan in a changing room cubicle at a public swimming pool.

His sadistic crimes were uncovered when he murdered new girlfriend Evie Adams, 23, by giving her a cocktail of prescription drugs.

Monaghan’s killing spree has now been explored in new documentary The Killer In My Home: A Deadliest Mums & Dads Special on Discovery+.

Never-before-seen footage from his police interview shows the lying dad brazenly telling officers how he watched the 1988 action film Die Hard starring Bruce Willis on the night Ruby died.

Monaghan said he was downstairs with the tot in front of the TV – even though he had already killed her.

When asked what he was watching, he says: “Yeah I was watching Die Hard.”

He then told cops he brought Ruby downstairs, adding: “On occasion, if we were staying up late, we’d bring the Moses basket down.

“It was comfy for her as well. And that night we were up to after midnight as it was New Year’s Eve.”

In reality, the killer had blocked Ruby’s airways with his hand as he smothered his baby daughter to death.

He told the tot’s mum Laura Gray, who was sleeping at the time, that he woke up to find her not breathing.

Ruby’s death was originally put down to a tragic accident as an result of acute bronchial pneumonia following an inquest.

In a double heartache for Laura, she discovered son Logan unresponsive in his pram after Monaghan struck again just eight months later.

Then, in 2018, a police investigation into their deaths was launched and Monaghan became the prime suspect.

With the help of brave Laura, officers were able to paint a picture of a controlling bully who would abuse his children if their relationship was rocky.

He would also make the kids ill so Laura would feel pressurised to stay.

In 2018, Monaghan was arrested on suspicion of murdering his two children.

Dramatic footage featured in the documentary shows the handcuffed brute asking “With what evidence are you doing this?” as he is detained.

But due to the “complexity of the case”, he was later bailed – allowing him to kill once more as he targeted girlfriend Evie Adams.

On October 24, 2019, Evie was discovered collapsed from a suspected drug overdose that had actually been planned meticulously by Monaghan.

He had poisoned his partner and forged a fake suicide note claiming to be from Evie in a murderous attempt to evade justice.

But officers were suspicious and drafted in a host of specialists to prove Monaghan was behind not just Evie’s death but also those of his two children.

Detective Chief Superintendent Pauline Stables tells the show: “We asked for advice from forensic pathologist, paediatric pathologist, neurologist, cardiologist, infectious diseases specialist, geneticist, all to rule out any potential natural cause for Ruby’s death.

“So ultimately the overall evidence supported that Jordan had obstructed Ruby’s airway through pinching her nose and putting his hand over her mouth.”

She continues: “We now know that Jordan has travelled to Waves, pushed Logan in his pram into a changing room within Waves, spent some time within the changing room at which point we believe that is where he’s obstructed Logan’s airway and ultimately killed him.”

Officers were also able to establish that Monaghan gave Evie tablets under the guise of making her better when she fell ill with a stomach ache before she died.

The monster was finally charged with three counts of murder in January 2021.

DCS Stables said: “Jordan’s physical reaction to being charged was… There’s no emotion, no emotion when going through the last moments of their lives.

“No emotion when reliving the deaths and the circumstances surrounding his three loved ones.”

Monaghan was jailed for life with a minimum of 21 years, which was later upped to 48 years, in December 2021.

• The Killer In My Home: A Deadliest Mums & Dads Special is available to stream from Saturday 1st April exclusively on discovery+

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