Captain Nicholas Steyn was testifying on the tenth day of the trial against 22-year-old Henri van Breda who has been accused of killing his mother, father and older brother with an axe.
His sister Marli, who was 16-years-old at the time, survived the attack with severe injuries, but has no recollection of what happened on January 27, 2015.
Steyn was called to the upmarket de Zalze estate after a report of a break-in.
The family home was located in the centre of the estate which had 24-hour security.
He told the court that when he arrived at the house he found it strange that cellphones, laptops and small items had not been stolen.
Steyn said he took a number of crime scene photographs. He described Henri as "quiet and calm" when he spoke to him in the ambulance.
Henri told him his version of events: while he was in the toilet an axe-wielding intruder had attacked his brother, his father had come running into the room, and the attacker then turned on him.
Henri claimed his sister and mother also ran into the room and they too were attacked.
Henri told Steyn he confronted the attacker and threw the axe after him as he fled down the stairs, but it hit the wall.
The intruder then fled out the back door, and when Henri returned upstairs and saw his family upstairs he fainted.
He claimed he googled emergency numbers when he woke up.
Steyn told the court a "balaclava gang" had been breaking into houses in the Stellenbosch area, but the last of them had been arrested in November 2014.
During cross-examination by defence advocate Pieter Botha, Steyn conceded that it was possible for an intruder not to leave a trace on the wall while fleeing the property.
Botha also said there was no blood on Henri's socks, which Steyn agreed.
The case was adjourned to Monday. Next week, the State is expected to lead medical and forensic evidence.