Detectives investigating the death of a teenager in Colchester are continuing to look for the murder weapon.
They are also want more teenagers present at the house party where the incident happened to come forward to speak to them.
A murder investigation was launched after Jay Whiston was stabbed at a party on Marlowe Way shortly after 10pm on Saturday, September 8.
The 17-year-old boy from Aster Close, Clacton died in hospital.
Officers have interviewed many of the partygoers in the days following the murder, but are still trying to pinpoint the sequence of events as they unfolded, as well as identifying the knife used in the murder.
Senior Investigating Officer, DCI Simon Parkes, said: "Many of the teenagers have given accounts of what happened on that Saturday night. These boys and girls are clearly key witnesses, crucial to our investigation.
"We have found that Facebook and Twitter have played a significant part in events leading up to and after this murder.
"We have arrested five people and cannot rule out arresting others. We are very much dependant on those who attended the party and those who subsequently heard about what happened coming forward."
Although a number of knives have been recovered from the local area, police do not believe any of them to be the murder weapon and so are appealing for someone to hand it in.
Five people from Colchester were arrested on suspicion of murder during the following days.
The two 18-year-old men and three 17-year-old boys have now all been released on police bail until Wednesday, October 17 pending further enquiries.