Police cars and a forensic van have been seen in The Triangle in Bournemouth since the evening of Monday, February 9 and into Wednesday, February 11.
Leicestershire Police have since confirmed the police presence is to do with an on-going murder investigation in its county.
The 25-year-old man from Bournemouth has been arrested on suspicion of murder.
A total of 12 people have been arrested in connection with the murder of a man, aged in his 60s, who has not been seen since April 2024.
It was said there has been no proof of life of the man since then.
Detectives and specialist officers remain at Broad Avenue in East Leicester, after searching two other addresses in Falmouth Road and Gwendolen Road, both in Evington.
A spokesperson for the force said there will be a significant amount of police activity over the coming days and weeks.
The searches will include digging into the ground in Leicester and involve building machinery, specially trained search officers and crime scene investigators.
Of the 12 people arrested, 11 remain in police custody and one woman, aged 23, has been released with no further action.
Eight men have been arrested on suspicion of murder and remain in police custody while they are being interviewed.
They are aged 61, 43, 34, 33, 23, 21 and two aged 25.
A ninth man, aged 50, has been arrested on suspicion of assisting an offender and also remains in custody, along with the two women aged 34 and 29.
Senior investigating officer, DI Michael Chander from the East Midlands Specialist Operations Unit, said: “Since carrying out the warrants yesterday morning there has been significant progress in this investigation, including clearing the areas of the property that we need access to and making them safe to allow a comprehensive search to be carried out.
“There’s still a lot of work to be done and detectives and Crime Scene Investigators are at the scene and will be over the coming weeks, ensuring a thorough investigation and evidence gathering.”
Anyone with information can contact Leicestershire Police on 101, quoting incident number 221 of 9 February 2026.