Ten incidents of possible police misconduct have been found by investigators looking into the killing of Jacqueline Oakes.
Marcus Musgrove was jailed in July 2014 for killing the 51-year-old.
A review was launched over her death, including contact she had with various agencies at the time.
The Independent Police Complaints Commission said it had issued notices to 26 serving West Midlands Police officers and seven police staff, advising them they are subject to investigation.
Notices have also been sent to an officer who has retired and to one who now works at another force.
An IPCC spokesman said its initial assessment had identified ten potential misconduct issues relating to incidents between April 2013 and January 2014.
"Our independent investigation is looking at whether the police officers and staff involved resourced, recorded and risk assessed the incidents in line with force domestic abuse policy," the spokesman said.
A domestic homicide review is also being carried out by Birmingham Community Safety Partnership.
Ms Oakes was discovered in a bedroom at Century Tower, Dollery Drive in Edgbaston, in January 2014.
The mother-of-four died from multiple blunt force injuries.
Musgrove, of Lichfield Road, Aston, aged 40 when sentenced, was told he would serve a minimum of 18 years.
At the time, West Midlands Police said he carried out the fatal attack after weeks of subjecting her to controlling and abusive behaviour.

The Society of Motor Manufacturers and Traders (SMMT) said sales were up 8.4% compared with February last year.
Sales of alternatively fuelled vehicles jumped 19.9% year-on-year, with diesels up 5.6%.
Fleet sales fell 1.4% but still accounted for 53.1% of new vehicle sales in the month.
SMMT chief executive Mike Hawes said: "February is typically one of the quietest months of the year ahead of March's plate change, but this positive performance is encouraging and puts the sector in a good position for the coming 12 months."
Samuel Tombs, chief UK economist at Pantheon Macroeconomics, said only 4% of cars typically were registered in February, so "small movements in the absolute number of registrations have a big impact on the headline growth number".
"High consumer confidence, lower petrol prices and cheaper unsecured credit have enhanced the attractiveness of car ownership, but these drivers will be less supportive of sales growth in 2016," he added.
"Growth in car sales therefore looks likely to moderate, contributing to a slowdown in the overall consumer spending recovery this year."
A record 2.63 million new vehicles were registered last year - about 6% higher than in 2014 and the fourth consecutive year of growth, according to the SMMT.
The top selling models in February were the Ford Fiesta, Volkswagen Golf and Nissan Qashqai.
VW sales were down 13% compared with February 2015, although Toyota recorded a 16% drop and Vauxhall a 17% slide.
Ford sales were 12% higher compared with February 2015 at 11,513 vehicles,

Land is being made available by Northern Ireland Executive.
One of two helicopters that will form part of the service toured Northern Ireland last week. The charity behind it says it hopes it will be fully operational by March next year.
The decision to choose the Maze site has been waiting for executive approval for some time.
It was given the green light following a test landing last week, which was used to assess several factors, including noise levels.
Northern Ireland was previously the only area in the UK without a HEMS (helicopter emergency medical service).
In March, the then health minister, Simon Hamilton said the air ambulance would be based at Belfast International Airport.
But the charity behind the new service believes basing it at the Maze will be cost effective.
It plans to use an existing building that was once used to check vehicles.
The helicopter has arrived after a campaign for an air ambulance service by the late Dr John Hinds.
Dr Hinds died in an accident in July 2015, but his partner Dr Janet Acheson continued his campaigning work.
The building at the Maze will be converted into hangar space for two helicopters, as well as changing facilities for crew and an operations room.
The charity Air Ambulance Northern Ireland says it will need to raise about Â£2m a year to operate the service.
Health officials have yet to decide if it will have doctors onboard as well as paramedics.
Thirty-five members and former members of West Midlands Police are being investigated over events that led to a woman's murder in Birmingham.
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Almost 84,000 new cars were sold in February in the UK - the highest level for the month since 2004.
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The new air ambulance for Northern Ireland is to be based at the Maze Long Kesh site near Lisburn, County Antrim.