Investigations by the Garda Síochána, who found UVF insignia on McDowell's coat, led them to question his associate Samuel Stevenson who named McKeague as a central figure in a series of UVF explosions that had been carried out at the time, many involving UPV members. The case went north, where the previous explosions had taken place, and on 16 February 1970 the trial opened.
The Garda Síochána conducted investigations finding UVF insignia on McDowell's coat, which led to questioning of his associate Samuel Stevenson. Stevenson identified McKeague as a key figure in UVF explosions that occurred at the time. The case moved northward, where previous incidents had taken place, and the trial began on February 16, 1970.