The police response to Joanna Michael's 999 call is being investigated
A man who killed his ex-girlfriend in a "frenzied" knife attack has been jailed for life at Cardiff Crown Court.
Cyron Williams, 20, admitted murdering Joanna Michael, 25, with police comparing the scene at her home in St Mellons to a horror movie.
His barrister claimed her life could have been saved if her 999 call had been handled more promptly. She had called after he had punched her.
The Independent Police Complaints Commission is investigating.
Williams was told he would serve a minimum of 20 years.
The court heard Williams had broken into the house in August 2009 and found Ms Michael in bed with another man. He then "calmly" gave him a lift home before returning to confront her.
Prosecutor Patrick Harrington QC said Williams, of Pentwyn, Cardiff, was in a rage after an all-night drinking session.
Mr Harrington said: "He went to her house unannounced and kicked his way through the door, went upstairs and saw she was in bed with another man.
"With some calmness, Williams gave that man a lift home before returning to the house where he went to the kitchen.
"He armed himself with a large kitchen knife, went upstairs and stabbed Joanna Michael to death."
Mr Harrington added that Ms Michael was "a popular young woman, vivacious, enthusiastic and a very good mother".
Cardiff Crown Court heard she had ended her "turbulent relationship" with Williams before seeing old school friend Lewis Yellen.
Mr Harrington said: "At 2.15am Lewis was woken by the bedroom lights being switched on.
'Emotional and confused'
"He looked up and saw Cyron Williams standing in the doorway."
Williams drove Mr Yellen home in Ms Michael's car at speeds of up to 100mph before returning to her house at St Mellons, Cardiff.
Mr Harrington said: "He was driving so quickly he crashed the car into the front of the house.
"He kicked open the front door, went into the kitchen and armed himself with the largest knife there."
Mr Harrington said it was a "brutal" murder with 22 stab wounds and a total of 74 injuries.
Cardiff Crown Court heard that the first policeman on the scene had said: "I can only describe it as something you would see in a war or horror film."
Defence barrister John Charles Rees QC said: "He was shocked to find her in bed with another man. He was angry, emotional and confused."
In a letter to the court, Williams said: "I know I will never be forgiven, I know I don't deserve it.
"I've devastated the lives of Joanna's family and my own mother. I will spend the rest of my life trying to do good and make up for what I have done. I am truly, truly sorry."
Judge Mr Justice Wyn Williams him: "You committed a terrible crime that night. You have deprived two children of their mother and Joanna's parents of a much-loved daughter."
The court heard Williams had punched Ms Michael in the face before driving Mr Yellen home, causing her to call police in fear after he had left.
But Williams returned before police arrived and carried out the murder, the jury was told.
Ms Michael phoned police at 2.29am from her Cardiff home, but her call was handled by Gwent Police rather than South Wales Police.
The Independent Police Complaints Commission (IPCC) is investigating the actions of both police forces.
Williams' barrister claimed that if her call had been handled differently she would still be alive.
To shouts of "No" from some of those in court, Mr Rees said: "It is a fact that if that first call had been dealt with promptly we would not be here today."
St Mellons borders onto the Gwent Police force area
An IPCC spokesman said at the time: "Because St Mellons is close to the border between the two force areas, the initial call went through to the Gwent Police control room, who contacted South Wales Police (SWP) to dispatch officers from the police station at Newport Road, Cardiff.
"The SWP police officers arrived at Ms Michael's home approximately 20 minutes after the initial call, but after she had been fatally stabbed."
Her parents Angela and Anthony Michael said after the case: "We are pleased that Cyron Williams has today been imprisoned for the unprovoked and mindless murder of our daughter Joanna.
"Our family was handed its own life sentence and no prison term will ever be sufficient for the incomprehensible devastation he has caused us."