Ten men are being questioned on suspicion of murder after a 39-year-old man was found dead near the site of the V Festival.
Detectives believe a private party was being held at the house in Chelmsford, opposite Hylands Park, at the time.
The dead man was found in the rear garden of the property just after midnight on Sunday. A post-mortem examination has revealed he died of head injuries and an inquest will be held at a later date.
The 10 men, who are aged between 23 and 35 and all from Essex, remain in police custody after being arrested.
Essex Police is appealing for anyone who was at the house, off the A414 London Road, to contact them.
Relatives of the victim, from Rayleigh, Essex, have been informed and are being supported by specially-trained officers.
Chief superintendent Glenn Caton said: "We do not believe there is a direct connection with the V Festival taking place at Hylands Park."
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