The case of a woman stabbed to death in Newmarket will be referred to the police watchdog because the victim had previously contacted Suffolk Constabulary.
A murder inquiry has been launched following the incident in Brickfields Avenue, Newmarket, on January 16, where the woman was found with stab wounds.
Police were called shortly after 9.30pm, with paramedics and the air ambulance attending the scene alongside officers, however the woman died at the scene.
A 28-year-old man was arrested on suspicion of murder and is being questioned by officers at Bury St Edmunds Police Investigation Centre.
Officers have now said the matter is being referred to the Independent Office for Police Conduct due to there having been previous contact between the victim and Suffolk Constabulary.
Suffolk police said: "Inquiries are on-going into the incident and investigations are at an early stage, but it is believed that the parties involved were known to each other."
Roy Collinson, 68, of neighbouring Highclere Close, said: "I was watching the snooker when I heard all the noise overhead from the helicopter. It landed on Brickfield Stud and my girlfriend went to the door to see what was happening, that's when we saw all the blue flashing lights and nine or so police cars came down the road. It was chaos.
"We don't even have burglaries here, it's a quiet area."
Mr Collinson also said he had seen police cars in Brickfields Avenue on the morning of January 16, before the stabbing.
James Black, who lives in the town, and is the father of one of the victim's neighbours, said: "My daughter had been back in her house about an hour, she'd just arrived home from a cruise.
"The police knocked at her door and asked if she could look after the dog."
He said his granddaughter played with a child living at the address where the alleged attack happened.
He added: "She (my daughter) hasn't been able to talk about anything else since, it really affected her."
A woman at the scene, who asked not to be named, said: "It is such a shock, this is a nice quiet area. It's just so sad to hear about."
Anyone with information about the incident or heard or saw any suspicious activity is asked to contact Suffolk police, quoting CAD number 400 of 16 January 2020.
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