Egyptian national Mariam Moustafa died on Wednesday after she was attacked in Nottingham on 20 February
A post-mortem into the death of an 18-year-old girl has returned an inconclusive result.
Mariam Moustafa was assaulted by a gang of six women and
died three weeks later.
She was punched several times in Parliament Street before she tried to escape by boarding the No 27 bus outside the Intu Victoria shopping centre. The gang of women, who were threatening and abusive towards her, followed her onto the bus.
More tests will now be conducted to establish if there was a link between the assault and her death.
Police said they were keeping an "open mind" about whether the attack,
which sparked outrage in Egypt, was racially motivated.
Egypt's Foreign Minister Sameh Shoukry said that the "painful incident" of Miss Moustafa's death "cannot go unpunished", adding that any officials responsible for medical negligence should also be held to account.
Nottingham University Hospital NHS Trust said its "initial review of this tragic case does not indicate any significant untoward incident on the trust's part, however we will fully examine the family's concerns."
A 17-year-old girl, who was arrested on suspicion of assault occasioning grievous bodily harm, remains on bail.
