Mr McCartney said: “This is another step forward in the long campaign for justice by the Bloody Sunday families. This is the first arrest to be carried out as part of the new investigation into the murders carried out on Bloody Sunday. “I would call on the PSNI to ensure the relatives are kept up to date of all developments on the investigations. “Sinn Féin will continue to support the Bloody Sunday families in the campaign for truth and justice.”