Police failed to fully complete inquiries before releasing a man who murdered his ex-partner two days later, an investigation has found.
Miklos Verebes, 29, killed Melinda Korosi, 33, at her Carlisle home on 15 September last year.
The Independent Police Complaints Commission (IPCC) said two Cumbria Police officers had cases to answer for misconduct.
The force said the officers had been given management advice.
Verebes had been released from prison on 13 September, where he had been sent after assaulting Ms Korosi earlier in the year.
He was arrested the same day over an allegation of rape made by Ms Korosi and later released without charge.
He was jailed for life in March.
The IPCC said: "There was evidence of a case to answer for misconduct for a detective constable and a detective sergeant in failing to consider all actions and potential lines of enquiry prior to the decision being made to release Verebes after he was arrested on suspicion of raping Ms Korosi."
The report said Ms Korosi's neighbours were not properly interviewed, medical and social services records were not examined and advice from the Crown Prosecution Service was not sought.
IPCC operations manager Catherine Bates said safeguarding measures were in place, but "more could and should have been done to ensure the decision to release Verebes was supported by all the available advice and evidence".
A Cumbria Police spokesman said the force accepted the action "amounts to misconduct for two serving officers".
"The sanction, which was agreed with the IPCC, was management action for both officers.
"This action, which is ongoing, consists of a formal recording of misconduct and a robust personal development plan. This is being managed by senior officers," the force added.