A 49-year-old Symonston man has been charged with murder following an altercation with a man known to him on Monday afternoon.

Police say that at about 5.30pm the 49-year-old man called from the Southside Village Caravan Park, saying a fellow resident was lying unconscious at his front door after the pair allegedly got into an altercation.

Police arrived and began CPR on the unconscious 34-year-old man before ambulance paramedics arrived and took over his resuscitation. He was taken to Canberra Hospital in a critical condition and died on Friday.

The 49-year-old was arrested at the scene and was charged with recklessly inflicting grievous bodily harm. On Friday, that charge was upgraded to one count of murder.

Detectives would like to speak to anyone who has information about the two men and their interactions, including anyone who may have spoken to either of them before 5.30pm on Monday.

Contact Crime Stoppers ACT or call 1800 333000.