Malachy Halpenny served with the Royal Field Artillery during the Great War, number 120000.
After his return to Belfast, he was to fall victim of the B Special/RIC Cromwell Gang reputed to be under the command of District Inspector Nixon. In June 1921, he was dragged from his bed and beaten. Halfpenny's feet were pierced by a bayonet to prevent any chance of escape. He was shot several times and his bullet riddled body was found in a field having been thrown on a barbed wired fence. 17 bullet wounds were counted.
According to a debate at Westminster, one brother had died during the Great War and 3 others had served.
http://hansard.millbanksystems.com/commons/1921/jun/14/crown-forces-belfast-2
James Halfpenny from Belfast was killed in June 1917 with the Royal Irish Fusiliers having been in the Connaught Rangers
A short while before his death, Malachy Halfpenny had appeared in the London/Edinburgh Gazettes
making progress in his job as a Postman
http://www.edinburgh-gazette.co.uk/issues/13685/pages/357/page.pdf
District Inspector John William Nixon was dismissed from the RUC in 1924. He went on to become a politician in Belfast Council and later an MP at Stormont.