John McBurney, from Green Park Avenue, Markethill, had faced four charges in total following the death of David James Shields in June 2016.
Mr Shields, who was aged in his 50s, was discovered on a grass verge just before 7am on June 13, 2016, at Shillington Road, Markethill.
At the time, police indicated it may have been the result of a hit-and-run.
McBurney had faced four charges but this week accepted his guilt on the lesser charge of driving when unfit through drink/drugs.
He also pleaded guilty to charges of failing to stop following an RTC; failing to report; and failing to remain at the scene of an accident.
Following a brief hearing at Newry Crown Court on Tuesday, the District Judge adjourned for pre-sentence reports to be prepared.
McBurney was released on continuing bail to appear back before Newry Crown Court on June 1 for sentencing.