A young mother was beaten to death by her violent ex-partner after police failed to intervene 11 times, investigators have said.
Casey Brittle, 21, repeatedly called Nottinghamshire Police before she was murdered by Sanchez Williams in front of her two-year-old daughter.
Amerdeep Somal, a commissioner at the Independendent Police Complaints Commission (IPCC), said Sanchez, from Nottingham, was "well-known to local police for his propensity for violence and threatening behaviour".
"In this case it is clear that a number of officers failed to perform to the level expected of them and basic actions, that may have helped others see the full picture of her suffering, were not completed," the commissioner said.
"No consideration was given to why Casey was reporting domestic abuse but then subsequently saying that she did not want police help."
Ms Brittle died from a series of injuries to her head, including a fractured jaw, cuts and bruising in October last year.
Williams, of Lathkill Close, Nottingham, was jailed for life after he admitted murdering Casey at her home.
Police received allegations of domestic violence and abuse against Ms Brittle between September 2008 and August 2010. The police watchdog recorded a number of force and individual errors.
An IPCC spokesman said: "As a consequence of the investigation, six officers faced misconduct for their roles in three incidents, while a further four officers have been dealt with through unsatisfactory performance procedures.
"Aside from failures by individual officers, the investigation identified the lack of a thorough corporate approach to domestic abuse from Nottinghamshire Police. This resulted in a lack of knowledge and support for officers in their attempts to provide victims with the necessary support."