Essex police said detectives investigating the murder of Jay Whiston have set up a dedicated number for witnesses to call.
Anyone with information is asked to contact the incident room on 01245 452882.
Up to 200 people attended the house party in Colchester were the murder took place. For more on this story go to ITV Anglia.
More top news
Jeremy Renner has joked that director Joss Whedon's task on The Avengers film set is like "herding kittens".
Monster hunters can now explore Loch Ness on Google Maps - but will you be able to spot Nessie?
An elderly and vulnerable man is fighting for his life after being mugged while riding a mobility scooter.