A woman wrongly convicted of an arson attack which killed a mother and her two children claims police distorted evidence to make a witness accuse her.
Ms Hewins said she just sought 'the truth' about the case
Annette Hewins is seeking compensation from South Wales Police in a civil action for malicious prosecution.
At the High Court sitting in Cardiff, she claimed police had told a teenager they had a strong case against her.
Diane Jones, her daughters Shauna, two, and 13-month-old Sarah Jane were killed in the blaze in Merthyr Tydfil in 1995.
Mother-of-four Ms Hewins, 40, from the Pant area of Merthyr, served almost three years of a 13-year sentence for the attack.
She and her niece, Donna Clarke, were cleared of murder but were convicted of arson with intent to endanger life. Donna Clarke was given a 20-year sentence. Their convictions were later quashed on appeal
Sarah-Jane and Shauna died with their mother Diana Jones
A third woman, Denise Sullivan, was convicted of perverting the course of justice and also jailed. No-one has since been convicted over the fatal attack.
In the hearing at Cardiff Civil Justice Centre, Ms Hewins' legal team argued that after four months' investigation, police had no clear suspects but under pressure for a result began to build a case against Ms Hewins and Ms Clarke.
The investigation turned its attention to Carly Johns, a 16-year-old associate of the pair, it was argued.
Hugh Tomlinson QC, acting for Ms Hewins, claimed Ms Johns was the most vulnerable of the group and was manipulated by police pressure to falsely incriminate his client.
He claimed that, during her 13th interview, Ms Johns changed her story significantly after being told by police that they had a strong case against all three, but she herself could escape prosecution if she incriminated the other two.
Giving evidence to the court, Ms Hewins broke down as she told of how several people, including police officers, told her on several occasions that they believed she was innocent.
She said that one officer made a comment which she claims suggested that he believed in her innocence. Moments later she was arrested.
She said: "I thought at the time that he genuinely meant that, but he picked his job over standing up for somebody who was innocent and that's what hurt."
She said suggested that officers in the case had been "embarrassed" by the investigation taking the line it did, while others had lied to her, saying that her niece had been charged, when she had only been arrested.
'Cast a shadow'
Under questioning by Simon Freeland QC, acting for South Wales Police, Ms Hewins admitted that she had been guilty of shoplifting offences, both before the arson and since she was released.
She is currently on bail for one offence of theft and another of possessing a controlled drug.
Ms Hewins' action against South Wales Police for malicious prosecution and misfeasance in public office was adjourned until Tuesday. The case is expected to last three weeks.
Before being freed by the appeal court, Ms Hewins spent more than two-and-a-half years in prison and she gave birth to her fourth child while in custody.
Ms Jones, who was 21, and her two young children died in the blaze after petrol was poured through the letter box of their home on Merthyr Tydfil's Gurnos estate on 11 October 1995.
Last October, on the 10th anniversary of the fire, South Wales Police renewed their appeal for information, saying the crime "had cast a shadow over the community of Merthyr".