Officers from British Transport Police have released CCTV images of a man seen walking along the train tracks between Metro stations on the Sunderland line in the early hours of March 1.
The man was seen walking on the tracks at Sunderland station at 5.40am. He was told to get off and climbed back up onto the platform then walked along the platform and went back on to the tracks towards Park Lane Metro Station.
After officers checked CCTV the same man was seen climbing onto the tracks at the Stadium of Light station at 5.19am before walking to St Peters Station, then through the railway tunnel to Sunderland. He then walked along the lines to Park Lane station where he eventually left the tracks.
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The constituency of Washington and Sunderland West includes the UK's largest car plant, which was opened by Nissan in 1984.
This seat was formed prior to the 2010 General Election, taking in Sunderland city centre and the Ryhope area to the south.
The constituency of Stockton South includes relatively affluent areas like Yarm and Eaglescliffe.