A teenager who was arrested in connection with the death of a Saudi Arabian student in Colchester has been released as detectives continue to search for a motive for the brutal stabbing.
Nahid Almanea, a 31-year-old student at the University of Essex, was found fatally injured on a path near Avon Way on Tuesday.
She had been stabbed 16 times in broad daylight and died at the scene from injuries to her head and body.
A 19-year-old man from Colchester was arrested on Friday afternoon over the death and questioned about an attack on a woman jogging nearby.
Essex Police said he would face no further action in relation to either case.
Another man, aged 52, who was initially arrested in connection with the death has also been “positively eliminated” from inquiries.
Police have called for calm in the wake of the stabbing as the possibility that she was targeted because of her traditional Saudi dress provoked fears of revenge attacks.
There were several threats on social networking sites, including a man claiming to be an Isis fighter in Syria who used Twitter to call for “any brother to take up knife to kill as they did” using the hashtag #Colchester.
Ms Almanea was wearing a hijab and a full-length navy blue robe, called an abaya, when she was knifed to death.
She arrived in Britain several months ago with her younger brother to study towards her PhD in life sciences at the university.
Detective Superintendent Tracy Hawkings said police were “conscious” her dress identified her as a Muslim but there was no “firm” evidence that she was targeted because of her religion.
More than 200 Saudi nationals study at the University of Essex, according to students.
The Student Union has its own Saudi society to help members with “culture shock” and to promote the country’s culture, according to its website.
Officers there were similarities between Ms Almanea's death and the murder of James Attfield, a vulnerable man with brain damage who died after being stabbed more than 100 times in a park in Colchester on 29 March.
No one has been charged with his murder.
Chief Inspector Richard Phillibrown, the town's area commander, said: ”I see this murder as an attack on the entire community of Colchester and I believe we will all pull together to respond to it.
“I am confident that the vast majority of people in this town will pay no attention to those trying to stir up trouble.”
Essex Police’s chief constable, Stephen Kavanagh, and the police and crime commissioner Nick Alston issued a joint statement, saying Colchester would remain “strong and united” through a distressing time.
They warned against jumping to conclusions about a religious or racial motive, calling it “deeply unhelpful, wrong and dangerous”.
CCTV footage showing Ms Almanea's last movements as she headed for the footpath on Tuesday morning has been released along with a map of her likely route from her home in nearby Woodrow Way, where she lived with her brother, to the Salary Brook trail, and a photograph of the bag she was carrying.
Anyone with information is asked to contact the Major Investigation Team on 01245 282103, Essex Police on 101 or contact Crimestoppers anonymously on 0800 555 111.