A man has been arrested in England over the 1974 murder of John Pat Cunningham.
Mr Cunningham died after members of an Army patrol opened fire in Benburb on Saturday, June 15, 1974.
The 27-year-old was seen as vulnerable and had a mental age of between five and 10 years. He was shot three times as he ran from the soldiers.
The accused is to be brought to Northern Ireland for questioning at the Serious Crime Suite in Antrim.
Two years ago the family received an apology from the Ministry of Defence but expressed anger that none of the troops had been disciplined.
The case was re-opened last month and a murder investigation started following an assessment of the available evidence.