Two rail workers have been arrested on suspicion of manslaughter following the Cumbrian train crash.
The men, aged 60 and 64, are both Network Rail employees and from the Tebay area of Cumbria, a few miles from February's crash site at Grayrigg.
They were arrested by detectives from British Transport Police (BTP).
A force spokesman said, "The 64-year-old man has been released on police bail pending further inquiries. The 60-year-old man is currently in custody."
One woman died and 89 injured when the London to Glasgow Pendolino express derailed in the Cumbrian countryside on the evening of February 23.
BTP has already arrested and bailed a 46-year-old man, also a Network Rail employee, from Preston.
The arrests relate to Margaret Masson, from Glasgow, who died in the crash.
The two track workers were members of the Rail Maritime and Transport Union which said it was "mystified" at the arrests.
The union claimed that systematic management failings, lack of resources and the imposition of unrealistic workloads were at the heart of the tragedy.
According to the RMT, the industry's own investigations have highlighted the need to tackle structural failings and to reverse spending cuts.
