Michael Hynes was born on the 25th May 1891 in the townland of Boginfin, Athlone, Co. Roscommon, to John Hynes, a farmer, and his wife Rose (née McManus). He was the second son and third born of a family of seven, having three brothers and three sisters.
On the 17th July 1911 Michael Hynes was appointed to the R.I.C. at the age of 19. He is recorded as being 5'9⅝" in height, and a farmer prior to joining. On the 23rd January 1912, upon completion of training at the R.I.C. Depot, Phoenix Park, Constable Hynes, 66009, was allocated to Co. Carlow, where he served in Bagnelstown and Carlow town. On the 1st February 1920 Michael Hynes was promoted to the rank of Sergeant at the age of 28. Following promotion he was transferred to Co. Clare on the 25th February 1920.
Michael Hynes died at the workhouse in Ennistymon, Co. Clare, on the 24th September 1920 at the age of 29 years. He had 9 years and 2 months of service and was single. He was buried in Drum Cemetery, Co. Roscommon.