A woman was raped at a premises at the junction of Velyn Avenue and the A259 Bognor Road around 7.30pm on Monday, September 19.
She continues to be supported by specialist officers while enquiries are ongoing.
Officers believe the person pictured may be a key witness and are keen to speak with them to see if they saw anything which may assist the investigation.
That person, or anyone who recognises them, is urged to get in touch with police online or by calling 101 quoting Operation Mountain.
Anyone who has any other information about the incident is asked to report it to police or anonymously via the independent charity Crimestoppers online or by calling 0800 555 111.
Ion Gheorghe Tanasie, 40, of Pound Farm Road, Chichester, has been charged with rape and is due to stand trial in June 2023.