A man has been blinded after a cup of acid was thrown at him by an attacker in south London.
Police are appealing for help in tracking a suspect following the attack on two men in Thornton Heath, Croydon.
Their attacker ran away and both victims were hospitalised following the incident shortly after 8am on 7 December.
One of the victims has permanently lost his sight, the Metropolitan Police said.
No CCTV of the attack has been identified but the force has issued an image of the suspect.
One of the victims said the same man had visited his home in September, claiming to have a letter for him.
When the victim collected it, the man punched him in the face with a bicycle chain wrapped around his fist.
Police say the identity of the attacker and his motive remains unknown.
The suspect is described as a white, or Asian, man in his 30s with a slim build.
At the time of the attack on 7 December he was wearing a blue medical mask, a long black jacket with the hood up, black trousers and shoes.
Anyone with information regarding this incident is asked to contact police on 101 or Tweet @MetCC quoting CAD1273/07DEC20.
Alternatively, information can be provided to Crimestoppers anonymously by calling 0800 555 111, or online by visiting crimestoppers_uk.org