An attack on an Egyptian student, who died three weeks later, was not hate-related, police have said.
Mariam Moustafa, 18, died on Wednesday, three weeks after she was allegedly punched repeatedly by six women on a bus in Nottingham.
Nottinghamshire Police said they do not know if an attack on Miss Moustafa and her sister in August is connected.
Meanwhile, about 150 people gathered at a vigil in Nottingham earlier.
A 17-year-old girl, who was arrested on suspicion of assault occasioning grievous bodily harm, remains on bail.
Supt Rob Griffin told a press conference: "All of the evidence indicates that the incident is not in any way hate-related."
He added police have a "very clear picture" about the attack on 20 February and have identified six suspects.
No-one was arrested after the previous attack in August as police did not know who the suspects were.
"We don't know whether or not it is connected at this time but we are open-minded on that subject," he said.
Mariam, who was studying engineering at Nottingham College, was left in a coma after the attack on February 20 and died on March 14.
A post-mortem investigation was inconclusive.
Scores of people, including Miss Moustafa's father Mohamed, gathered in Nottingham's Old Market Square for a vigil.
Mr Moustafa said: "It is difficult for my family, it's broken our heart. We feel very upset
"This support makes me happy, we've met a lot of people supporting me and my family."
Miss Moustafa was born in Rome, where her family had moved from Egypt in 1991.
Italian prosecutors have opened an investigation into her death.
Supt Griffin said he will be having conversations with both the Egyptian and Italian embassies throughout the week.
Mr Moustafa, has called for "justice" for his daughter, who was "very kind" and "like an angel".