British Transport Police (BTP) is continuing its search for a man they believe sexually assaulted a 14-year-old girl on a London underground train between Elm Park and West Ham.
The attack happened in October last year on a District Line service and police have renewed their efforts after combing CCTV footage and releasing an image of the suspect.
The victim was travelling on the westbound line while the offender changed trains and alighted at Canning Town. Officers would like to speak to the man shown in the CCTV images as he may have information which could help with the investigation.
They believe he commutes from Becontree Station in Dagenham and are appealing for other passengers to come forward.
Investigating officer, PC Ben Martin-Richmond, said: "Our investigation is on-going and enquiries so far have led us to believe that the offender frequents the Becontree area, at various times of day and night.
"I am appealing specifically to people in the local area and anyone who uses Becontree station, as they may well be able to help identify the offender.
"I would like to hear from anybody who recognises the man shown in the CCTV images – I am sure that somebody knows who he is and it is very important that we speak to him as he may have information which could help the investigation.
"A child was sexually assaulted on a Tube. This is completely unacceptable and something that nobody should have to experience. If you know anything that could help us to find the person responsible, I urge you to please come forward."
If you recognise the man or have any information about the incident, please contact British Transport Police by calling 0800 40 50 40 or text 61016, quoting reference number 323 07/12/16. You can also speak to Crimestoppers anonymously on 0800 555 111.