Police missed opportunities to intervene in the months leading up to a man shooting dead his estranged wife, an independent watchdog has found.
Christopher Parry shot wife Caroline twice in the back after she had called time on their marriage after being fed up of his controlling and domineering ways.
The 50-year-old licensed gun holder then turned the weapon on himself, but was left with severe injuries in a botched suicide attempt.
His trial at Newport Crown Court heard in the weeks leading up to the tragedy, Mrs Parry had contacted police three times over fears about her husband's behaviour.
A report by the Independent Police Complaints Commission (IPCC) said Gwent Police needed to make improvements to the way it handled stalking and harassment cases.
It made four main findings - saying officers responding to incidents involving the couple not having "all the relevant information" about their past history.
It also said police should have given greater consideration to Parry's coercive behaviour and carried out more checks on his firearms license.
IPCC commissioner Jan Williams said: "This was a callous, brutal murder that devastated Caroline's family and friends.
"Our investigation found weaknesses and shortcomings in how Gwent Police handled this case and it is not the first time the IPCC has raised concerns over how the force responds to domestic abuse cases.
"The force has given a higher priority to domestic abuse cases, but I am urging senior officers again to ensure they take all necessary steps to improve their performance."
The shooting took place in Seabreeze Avenue, Newport, south Wales, on August 8, 2013.
Mrs Parry had been living in the newly built red-brick estate after moving out of the home she shared with her husband six miles away in Croesyceiliog, near Cwmbran.
But despite being told on April 12 their relationship was over, Parry refused to accept his marriage had ended and was "convinced" she still had feelings for him.
He kept his wife under surveillance and was described as a man "not prepared to let go".
In the weeks leading up to tragedy, he repeatedly texted, phoned and even followed his wife.
On the day in question, Mrs Parry was leaving for work when something suddenly caused her to stop and open the boot of her red Toyota.
It was then her estranged husband got out of his Ford Focus and pulled the trigger three times.
Neighbours later found the couple's bloodied bodies lying side by side on the road.
Mrs Parry was pronounced dead at the Royal Gwent Hospital.
Parry, who put the shotgun under his jaw, survived - but with substantial injuries.
The IPCC said its report looked at how Gwent Police had dealt with three incidents in the run up to the murder.
It highlighted that officers had failed to make referrals to the Firearms Licensing Department, which might have led to Christopher Parry's firearms licence being withdrawn before the fatal shooting.
It also said a risk assessment should have classified Caroline Parry as being "at high risk of serious harm" and more consideration " should have been given to Christopher Parry's coercive and controlling behaviour".
Another problem the IPCC found was the way in which it had a ratings system called "firearms warning markers".
The watchdog said: "M arkers only appeared on incident logs if the report was made from the address to which the firearms certificate was registered.
"Victims of domestic abuse who are estranged from their partners will invariably live at a different address, and so may not benefit from the degree of protection given by such markers which are important in alerting officers to a potential risk."
The IPCC's investigation concluded one officer had a case to answer for misconduct. Gwent Police said they had "already dealt with the matter".
Parry was handed a life sentence with a minimum of 26 years.
When eventually eligible for parole in 2040, he will be 76-years-old.
Sentencing judge Mr Justice Wyn Williams told Parry: "By your actions you have deprived your wife of her life, your daughter and son of their mother, and brought grief and unhappiness to very many people, and your own life is in ruins."