Experts investigating the cause of a train crash in Spain that killed 40 people have found a broken joint on the rails. The tail end of a train heading from Malaga to Madrid derailed at 7.45pm on Sunday, smashing into an oncoming train travelling from the capital to Huelva. Investigators at the scene identified some wear on the joint between sections of the rail, known as a fishplate, which they said showed the fault had been there for some time, a source briefed on the investigations told Reuters. They ‍found that the ‌faulty joint created a gap between the rail sections that widened as trains continued to travel along the track, which was renovated in May as part of a €700m (£608m) project. Technicians believe the faulty joint is key to identifying the precise cause of the high-speed crash, the source added. The first carriages of the train that derailed, operated by Spanish firm Iryo, drove over the gap in ‌the rails. But the eighth, ‍and last, carriage derailed, bringing with it the seventh and …