A 27-year-old man from Middlesbrough has been arrested on suspicion of endangering railway safety after a bottle containing hydrochloric acid was left on a train.
Middlesbrough railway station was cleared and the Northern Rail service to Darlington evacuated after the corrosive liquid was found on Sunday evening, sparking a major response by the emergency services.
British Transport Police released two CCTV images of a man officers wanted to trace, and a man has since been arrested on suspicion of endangering safety on the railway.
"We would like to thank members of the public for coming forward with information, as well as the media for assisting with our appeal.
The man remains in custody and is currently helping police with their inquiries."
More top news
Hundreds of people have been sharing their views at a public meeting following the closure of a GP practice in rural Northumberland.
On the first day of the meteorological Autumn - what will the weather have in store?
Fans are being warned that counterfeit Rugby World Cup tickets are in circulation. Here is some advice on how to avoid being conned.