Police have arrested a 16-year-old boy on suspicion of murder over the deaths of two teenagers at a house party in Milton Keynes.
This comes after two others - Earl Bevans, 22, and Charlie Chandler, 21 - have already appeared in court having been charged over the alleged murders of Dom Ansah and Ben Gillham-Rice.
In a statement, Thames Valley Police confirmed the arrest was in connection with the investigation into the killings of the two 17-year-old boys at a house party just before midnight on Saturday, October 19.
A spokesman for Thames Valley Police said: "A 16-year-old boy, from Milton Keynes has been arrested on suspicion of murder and is currently in custody.
"This is in relation to an incident in Archford Croft, Emerson Valley on Saturday 19 October in which two 17-year-old boys, named as Dom Ansah and Ben Gillham-Rice, sadly died."
Mr Ansah died from a stab wound to the back while Mr Gillham-Rice was knifed in the chest. One of the boys died at the scene and the other in hospital several hours later.
Ryan Brown, 23, and a 17-year-old boy, who cannot be named for legal reasons, were left with serious but non-life-threatening injuries.
Bevans, of no fixed address, is charged with two counts of murder and two counts of attempted murder.
Chandler, of Fitzwilliam Street, Bletchley, is also charged with two counts of murder and two of attempted murder.
In a previous appeal, Thames Valley Police Detective Chief Superintendent Ian Hunter, head of crime for the force, said: "We are still looking for others and they know who they are. I want to appeal directly to those people. We are looking for you and we will find you, however long it takes.
"At this stage we have not released your names or photographs, so please hand yourself in to the nearest police station as soon as possible.
"This is not going to go away and if we have to, we will name you so there will be no place for you to hide."
DCS Hunter said there were still "very important" witnesses who had not yet come forward with vital information about the incident - and some who were "refusing to assist".
He added: “I know there will be various reasons for being reluctant to get involved but please, please think about the fact that Dom and Ben have been killed and how you would feel if this was your family.
“I imagine you would want justice and you wouldn’t want people to get away with what they have done. I am sure you would want justice for your own family.
“I would ask therefore for you to think about this and do the right thing."
