Sussex Police has released images of the suspect believed to be involved in the noxious substance assault in Brighton.
Officers responded to a report of a substance being thrown over a woman in the doorway of a property in Steine Gardens around 4.20pm on Thursday (20 May).
The victim, a woman in her 20s, was taken to hospital where she remains with potentially life changing injuries.
Witnesses have described the suspect as a black woman, 5’6”, carrying a blue rucksack and wearing a face visor.
Brighton and Hove Chief Inspector Nick Dias said: “Our officers continue to work tirelessly to identify the suspect in relation to this matter and ensure an arrest is made.
“We need your help in identifying the person in the footage, do you recognise them?
“We believe the suspect fled towards Princes Street, Brighton, and then towards the seafront. We are urging anyone who witnessed someone acting suspiciously in this area between the hours of 3pm and 5pm on Thursday (20 May) to make contact with us.
“Patrols continue to be stepped up in the city, please do come and talk to one of us if you have any information or concerns.”
Anyone with information is asked to report in online or call 101 quoting Operation Overstone.