A Tube passenger was knocked unconscious and needed emergency surgery after being pushed off a train at West Ham.
The 60-year-old victim, who had been involved in a row on his way home to Barking, was shoved hard out of the carriage when the District line train was in the station.
Investigating police said he hit his head on the platform and suffered serious injury.
He is still in hospital in a stable condition but has significant memory loss.
British Transport Police are appealing for information about the incident at about 9.20pm on Friday, February 10.
A CCTV image of a man officers want to speak to in connection with the incident has been released.
The suspect is described as white, in his late twenties or early thirties and believed to speak with an east European accent.
Anyone with information should call police on 0800 40 50 40, quoting background log B9 of 20/02/2012, or Crime-stoppers on 0800 555 111.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here