The brutality of the two murders in Colchester suggests that police are hunting the same killer for both crimes, a leading criminologist has told Sky News.
Professor David Wilson told Sky News that both Nahid Almanea and James Attfield were "overkilled" - meaning they were stabbed many more times than was necessary to take their lives - indicating a link.
And he warned the murderer is unlikely to stop killing until they are caught.
He said: "Luckily murder is a very rare event in Britain and usually we discover that there is some kind of relationship in the past between the perpetrator and the victim.
 Prof Wilson said Mr Attfield's murder could hold the key to both killings  "So here we've got something really unusual happening in Colchester - we've got two random attacks in a very concentrated geographic area and both victims have been 'overkilled'.
"They've been stabbed numerous times - more times than would be necessary to actually take their life.
"Clearly there is some link between these two, although the police don't want to make that link because it scares people to think there might be somebody of this background at loose in the community."
 CCTV footage issued by Essex Police of Nahid Almanea  He said the killer is likely to be a local man with mental health problems who may be known to social services in the area - and even getting help from someone in the community.
He told Sky News: "Murder is an overwhelmingly male phenomenon so I would have thought this is a man we're dealing with and a man who's living locally and possibly being given support locally.
"Usually when you're dealing with someone who stabs in this overkill way, you're dealing with somebody who's got mental health problems and this person is likely to be known to mental health outreach teams in Essex, perhaps also has a criminal record already.
"This type of person I think will be well known in the area and quite odd - the sort of person people would notice. I imagine the police are already aware of who those kinds of people in Colchester might be.
People living in the area should follow advice from the police to avoid walking alone in isolated areas because the killer is likely to strike again, Prof Wilson said.
 The killer probably lives in the local area, Prof Wilson said  He said: "One has to balance scaring people - the police have been quite good at telling people not to go into isolated areas by themselves but yes, this kind of person doesn't stop attacking, this kind of person continues to attack until they are caught."
He added that in most multiple murder cases, the first killing is key to tracking down the murderer.

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