A man arrested in connection with the brutal murder of Saudi Arabian student Nahid Almanea has been released, police said.
The 52-year-old man has been positively eliminated from enquiries, Essex Police said.
Nahid, 31, died after she was stabbed 16 times as she walked along a path in Colchester, Essex, on Tuesday morning.
She had been studying an English language course at the University of Essex as part of her studies for a life sciences PhD.
Essex Police say they cannot yet be sure whether Saudi Arabian student Nadid Almanea was killed because she was wearing Muslim dress. It is one line of inquiry, they say.
Nahid's body was found on a footpath in Colchester on Saturday. She had been stabbed 16 times.
Speaking at a press conference today, Essex Police also said they were investigating whether her death was linked to another fatal Colchester stabbing in March.
Essex Police have advised people in Colchester not to visit isolated places alone, after two fatal knife attacks in the town in three months.
Nahid Almanea, 31, was found on Saturday near the University of Essex campus. She had been stabbed 16 times.
James Attfield, 33, was stabbed 100 times in Castle Park in March.
Police say a man in his fifties is helping them with their inquiries.
Police are investigating the possibility that a woman who died after being attacked on a footpath was targeted because of her Islamic dress.
Although officers said there was no "firm evidence" of the attack being motivated by the victim's religious dress, they said this was one of "the main lines of investigation".
"We are conscious that the dress of the victim will have identified her as likely being a Muslim and this is one of the main lines of the investigation but again there is no firm evidence at this time that she was targeted because of her religion," Detective Superintendent Tracy Hawkings said.
The woman, who was in her early 30s, died after suffering head and body injuries in the attack on Tuesday morning on a footpath in the Essex town of Colchester.
Essex Police confirmed she was wearing a dark navy blue full length robe called an Abaya, and a patterned multi-coloured Hijab headscarf.
Essex Police have confirmed that the missing wolf from Colchester Zoo has been "found and destroyed" by zoo staff:
Sadly, the search for a wolf @colchesterzoo concluded shortly after 4pm when the animal was found + destroyed by zoo staff.
A wolf that escaped from Colchester Zoo earlier today has been shot dead, ITV Anglia report.
Five wolves in total escaped from their enclosure this morning. One returned, another was recaptured and two were shot earlier this afternoon.
There are unconfirmed reports that a wolf that escaped from Colchester Zoo has been shot dead and was seen being loaded into a 4x4 vehicle, local press reports.
Colchester Zoo has refused to confirm on the reports while it prepares a statement.
Police have launched a criminal investigation into the alleged manipulation of cancer waiting lists at a hospital in Colchester.
The investigation into Colchester Hospital University NHS Foundation Trust will aim to establish whether any criminal offences have been committed. The hospital was placed into special measures after the allegations came to light last month.
Colchester Zoo said it was "devastated" by the death of two of their "beloved" Timber wolves.
The two wolves were among five that escaped their enclosure this morning at around 7.30pm. In a statement, the Zoo said they were still looking for one of the escaped wolves, with the help of police.
One of the wolves returned immediately of its own accord and one was darted and recaptured.
Unfortunately, as they were further away and an anaesthetic dart takes 15 minutes to take effect, two had to be shot.
The remaining wolf is thought to be sheltering in thick undergrowth and the police are assisting in its recapture. Wolves are naturally timid and provided they are not cornered in any way do not provide a risk to the public.
Five wolves managed to escape from Colchester Zoo after the perimeter fence was damaged.
Two of the wolves were shot and killed, one was recaptured while the other returned voluntarily.
Essex Police are searching for the remaining wolf who is thought to be sheltering in thick undergrowth.
A police helicopter has been deployed to assist with the search.
For more on this story visit ITV Anglia