A man found guilty of killing two former girlfriends, five years apart, following a long campaign for justice by his second victim's family has been jailed for life with a minimum term of 25 years.

Judge Mrs Justice Simler said Robert Trigg, 52, was responsible for causing the two women's “senseless deaths”, and then lied about the circumstances.

Unemployed Trigg murdered Susan Nicholson, 52, in 2011, five years after he killed mother-of-four Caroline Devlin, 35, in her bed.

Foul play was ruled out following both deaths in Worthing, West Sussex, and Trigg, who has a history of domestic abuse against women, was initially treated as a bereaved partner rather than a suspect.

The death of Ms Devlin, whose body was found by one of her children on Mother's Day 2006, was originally recorded as being due to natural causes, an aneurysm, following a post-mortem examination.

And an inquest held in 2011 into Ms Nicholson's death ruled she died accidentally after Trigg claimed he inadvertently rolled on to her in his sleep while they were on a sofa.

But Ms Nicholson's parents refused to accept their daughter died accidentally and they launched a five-year campaign to challenge the inquest's conclusion.

Ms Nicholson's father, Peter Skelton, said they hired their own experts, including a pathologist and barrister, to prove she was murdered because the police would not listen.

His motivation for pursuing the case stemmed from his deep suspicions over how a heavily-built man like Trigg could roll over and suffocate his daughter on a narrow sofa.

Mr Skelton's persistence finally paid off as he saw Trigg, of Park Crescent, Worthing, convicted on Wednesday of his daughter's murder and Ms Devlin's manslaughter following a 10-day trial.

As he was led into court in handcuffs to be sentenced, Trigg said cryptically: “Isaiah 50, verse 11. They should be in here, not me.”

Sentencing Trigg on Thursday, Mrs Justice Simler told him: “The grief and sadness of these two families will never leave them.

”These were senseless deaths and nothing can now restore their lives, nor can any part of this sentencing process restore them either.

“What you, the defendant, will do, I hope, is reflect on his role in causing these senseless deaths.”

Ms Nicholson used to work at the exclusive Coutts bank and was promoted to the stocks and shares department before leaving banking to start a family. She had two sons.

In a victim impact statement, Ms Nicholson's mother, Elizabeth Skelton, said the family wanted answers over why she and her husband, both in their 80s, were able to bring Trigg's case to court and not the police.

She recalled hearing the news of her daughter's death, saying: “It was beyond belief. It was hard to accept that she was no longer with us. She wasn't just our daughter but our friend as well.”

She said the fight for justice had caused “mental torture” which triggered a mild heart attack in her and caused depression in Ms Nicholson's brother.

In her statement, Mrs Skelton added: “Our fight still goes on. We want answers to unexplained questions and why it was that the police weren't able to bring it to court when us, Sue's parents in our 80s, managed to.”

In a separate victim impact statement, Ms Devlin's son, Brandyn McKenna, said: “Our final message is that we don't want to think of our mother as dead and her memory will live on in our hearts forever.”

Mrs Justice Simler praised Ms Nicholson's family for “doggedly” pursuing the case.

She said: “Mr and Mrs Skelton, her parents, have fought doggedly and continuously since their daughter's death for the police to re-investigate her death, classified as non-suspicious and accidental at the time.”

The judge added: “The efforts of Ms Nicholson's family led to a review and re-investigation of her death and its cause, and you were not arrested until November 2016 in consequence.”

Sussex Police have apologised for not presenting all the facts to prosecutors following the original investigation, and Mr Skelton has not ruled out taking civil action.

The trial heard that both women's causes of death were re-examined years later by pathologist Dr Nathaniel Cary, who concluded that Ms Nicholson was suffocated by having her head forced into the bed.

In Ms Devlin's case, Dr Cary found her death was caused by a blow to the back of her head.

Trigg denied both charges but declined to give evidence in his defence.

Similarities were highlighted about the two cases at the trial, including the revelation that Trigg failed to dial 999 in either case after the women's bodies were found.

Jurors also heard that both women suffered domestic violence at the hands of Trigg during their relationships with him.

After one outburst, Ms Devlin said: “I won't be here for my 40th.”

Trigg was described as a “possessive, controlling and jealous” man and by one former girlfriend as a “Jekyll and Hyde” character who drank heavily.

Ms Devlin's friend, Bridget Benger, said her personality changed after she started a relationship with Trigg, describing her as becoming “withdrawn” and having “lost her spark”.

Three weeks before Ms Devlin's death, Ms Benger made a pact with her, promising that if anything happened to them, they would support each other's children.

Ms Benger said she found out about the discovery of her friend's body from Ms Devlin's eldest son, who knocked on her door, telling her: “We can't wake Mummy.”

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After Ms Nicholson died, Trigg instead went out to buy cigarettes, then called his brother Michael before phoning neighbour Hannah Cooper, telling her: “It's Sue, I think she's dead.”

Ms Cooper said Ms Nicholson and Trigg had a “volatile and violent” relationship, with rows fuelled by alcohol, and police had been called at least six times following bust-ups between them.