Police repeatedly failed a stalking victim who went on to kill herself, crushed by the weight of harassment she was suffering, a report has found.

Nicholas Allen subjected his former partner Justene Reece, 46, and her friends to a campaign of threats and harassment between September 2016 and February 2017, which ended only after she took her own life.

Thirty-four incidents were reported to Staffordshire police, including a threat Allen made to “put a bullet in someone”, but police failed to take decisive action to stop him.

Only after Reece’s death was Allen, 47, charged and convicted of manslaughter, coercive behaviour and stalking, and jailed for 10 years. Reece killed herself in February 2017, leaving a note saying she had “run out of fight” after six months of threats and harassment.

The Independent Office for Police Conduct (IOPC) on Monday released limited parts of its report.

Allen had even breached a non-molestation order (NMO) meant to protect Reece from him after she had first attempted suicide, the IOPC said.

The NMO had been obtained in November 2016, with Allen taking weeks to break it three times, all reported to police.

The IOPC concluded that errors in the way the force held the information or how it was searched for on its systems meant officers trying to assess how dangerous Allen was had only a fraction of the information.

It said 16 incidents were not linked on the force’s systems to previous incidents, and of the remainder, many were linked to one other incident rather than to all of them.

Stalking and harassment are old issues for police and in Reece’s case key policies meant to protect women such as her were not followed. Thus, a mandatory domestic abuse risk assessment was not carried out after six incidents, and they should have been.

The IOPC said one officer, now retired, could have faced disciplinary proceedings after the failure to arrest Allen after he broke an NMO in December 2016: “We were of the opinion there was an indication that an officer may have behaved in a manner which justified the bringing of disciplinary proceedings.

“This was because they had taken a decision not to arrest the woman’s ex-partner when he was in breach of his non-molestation order, after assessing that the woman appeared to have gone out willingly with him. Additionally, a number of complaints were raised about incivility and advice given that caused evidence to be lost, which related specifically to this officer.”

The IOPC said seven officers and one civilian staff member should receive management actionincluding training.

It said: “A number of issues were also identified as unsatisfactory performance for other officers. This included a failure to record a crime; a failure to take appropriate steps following an application for disclosure under the domestic violence disclosure scheme; a number of failures to complete mandatory domestic abuse risk assessments with the woman; and a failure to adequately recognise a breach of the NMO.”

The IOPC believed the failings were primarily systemic: “There had been inconsistencies in when incidents and crimes were linked on police systems. This had made it more difficult for staff and officers to appreciate the nature and scale of the ex-partner’s offending. Similarly, there had been a failure to consistently conduct lateral research and checks when incidents were reported. We recommended that this should be addressed by way of immediate training for all staff in the call centre environment.”

At Allen’s trial, the court heard he and Reece began dating in 2015 but she left him in 2016 because of his controlling and coercive behaviour.

Reece moved to a woman’s shelter, with Allen reacting by trying to hunt her down and stalking five people close to her in an attempt to track her down. He made 3,500 attempts to contact Reece via calls, texts and social media messages.

Allen even visited their homes, threatened Reece’s son, contacted employers and falsely accused a family member of serious sexual offences.

Allen had numerous previous convictions for offences committed against women dating back to December 1998.

They included making threats to kill, headbutting a former partner, breaking her nose, and threatening to set fire to a harassment victim’s father’s house.

Derrick Campbell of the IOPC said: “It is evident from our investigation that there were potential opportunities for the police to engage more robustly with Mr Allen.

“Officers were largely deployed to incidents appropriately, but a failure to cross-reference incidents led to them being treated in isolation, and a lost opportunity to recognise the scale of Mr Allen’s offending. The bigger picture of the level of harassment and stalking being perpetrated was not properly seen by police. We took the view that the prevalence of inconsistent practice among call handlers in cross-referencing indicated a training issue for the force, rather than a series of unrelated errors by individuals.“