Forty police officers swooped on addresses this morning, arresting four people on suspicion of beating a Mid Sussex mother to death.
The three men - two aged 32 and one 26 - and a woman aged 26, were arrested by squads at four different properties in Crawley.
They are suspected of murdering Charmaine Dempsy, of Ivory Walk, Bewbush.
The arrests come 16 days after Ms Dempsey, 48, was found dead at her flat on Sunday December 29 at 7pm.
A post-mortem examination revealed Ms Dempsey suffered multiple injuries consistent with a severe beating.
It is believed Ms Dempsey had been dead for more than a month before she was discovered.
Her 25-year-old daughter found the badly decomposing body when she let herself into the flat.
Sussex Police have up to 60 officers and police staff working on the murder investigation, codenamed Operation Fallow, and are still appealing for information.
The four suspects are being held at different custody centres across Sussex.
Detective Chief Inspector Tony O'Donnell, of the Sussex Police Major Crime Branch, said: "This is a significant breakthrough in the inquiry which we have been working towards over the last couple of weeks.
"At this stage these people have been nominated as suspects because of the evidence we have collated.
"I am still appealing to anyone with information to come forward in respect of this.
"There may be people out there who have information which they think is not relevant. I am urging those people to get in touch with us and let us decide."
There is a £5,000 reward for information leading to the conviction of Ms Dempsey's killers.
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