A girl was dragged to a field and raped in Rayleigh, with the teenager breaking a three year silence to report the incident.
Detectives have now launched a rape investigation after the girl came forward.
The incident happened when she was 13 on February 24, 2011 but she was too traumatised to report it until she confided in her family earlier this month.
She was walking home at about 9.30pm when she was assaulted by five men, aged between 25 and 35, in an alleyway between Bardfield Way and Langham Drive.
She was then dragged to a nearby field and assaulted again.
Police have issued an efit of the ringleader of the group.
Anyone who recognises the man should call police on 101.