Daniela Espirito Santo died after her boyfriend assaulted her hours after he was released on bail for attacking her earlier in the day.
Family and friends believe Ms Espirito Santo was repeatedly failed by authorities who were meant to protect her.
A watchdog report obtained by the New York Times and seen by Channel 4 News shows Ms Espirito Santo contacted the police about her boyfriend seven times in the year leading up to her death in Grantham in April 2020.
Julio Jesus was charged with manslaughter but this was later dropped because prosecutors said an “evidential link” between Ms Espirito Santo’s heart failure and his physical attacks could not be proved.
He was sentenced to 10 months in jail for two counts of assault.
Ms Espirito Santo was one of 16 women to die in the first month of lockdown last year in suspected domestic killings – the highest figure in a decade.
The Independent Police Complaints Commission report found no evidence to suggest police caused or contributed to Ms Espirito Santo’s death, but it said officers’ decision-making on the day she died may have influenced circumstances.
A Lincolnshire Police spokesperson said they would not comment on the report’s findings in case they risked prejudicing an upcoming inquest into Ms Espirito Santo’s death.
Campaigning lawyer and founder of the Centre for Women’s Justice charity Harriet Wistrich says Ms Espirito Santo’s death highlights the systemic failures in the way authorities deal with domestic violence cases.
In the space of just under 12 months, Ms Espirito Santo called the police seven times about her boyfriend, with the first one on May 19, 2019, when she was pregnant with her second child.
She told officers he had threatened to kill her, he was violent and controlling and “excessively jealous.” But she did not want to press charges.
Ms Espirito Santo would often call Charly Price-Wallace, who she had been friends with since secondary school, after the attacks.
Ms Price-Wallace said: “There was one attack that she told me about where he strangled her so hard that the imprint of his jumper was bruised to her neck. And she said at that moment he was going to kill me.”
On the morning of April 8, 2020, Ms Espirito Santo called emergency services to say Mr Jesus had thrown her on the bed and grabbed her neck. She agreed to support a prosecution.
Hours later Mr Jesus was arrested and taken into police custody before being released on bail with conditions not to contact the victim or attend her home.
When Ms Espirito Santo found out Ms Jesus was being released she called Ms Price-Wallace.
She told this programme: “My last words to Dani were: ‘You need to get out, you need to stick to this, because if you don’t, he’ll kill you.’ And they haunt me.”
Mr Jesus returned to Ms Espirito Santo’s home just over two hours after being released and he attacked her again.
Three hours later she made a final call for help. As Mr Jesus had left her home, the case was not considered urgent and she was told to call a non-emergency number.
Her call stayed on hold for eight minutes, and when the operator picked up, the only sounds were the cries of her baby.
She was later found unresponsive by the police and pronounced dead at the scene.
Ms Price-Wallace said: “Ultimately she died while on hold.”
A Crown Prosecution Service (CPS) spokesperson said Mr Jesus was originally charged with manslaughter “on the basis his actions that day triggered a fatal complication from a pre-existing heart condition”.
However, the defence’s legal team commissioned a consultant cardiologist to review the case who advised that a “verbal altercation or stress may also have led to Ms Espirito Santo’s heart failure”.
This meant the prosecutors could not prove an “evidential link” between Mr Jesus’s actions and her heart failure, meaning their “legal tests were no longer met” and the manslaughter charge was dropped.