Johnny Jooste, 35, the man suspected of killing seven people in the Koue Bokkeveld in the Western Cape, is to appear in the Ceres Magistrate's Court on Tuesday.
Jooste is expected to be charged with seven counts of murder, Captain Anton de Kock said.
Police completed their initial investigation on Monday, he said.
After holding a farming community in the grip of fear for more than 24 hours, Jooste walked out from under a tree near a crowded school playground and meekly surrendered to the principal on Monday morning.
Jooste, who eluded a massive manhunt involving dozens of policemen including elite task force members, tracker dogs and helicopters, gave himself up within sight of the police command centre.
Still carrying the 9mm pistol he allegedly used to end the lives of his wife and two young children, his wife's three sisters and one of their husbands, Jooste walked into the office of Abie Klink, the principal of Skurweberg Secondary School, and asked him to call the police.
According to Klink, Jooste had been hiding under a bush in the school grounds since early that morning and had intended handing himself in. He told Klink that policemen had walked pass the bush several times.
Klink said when he first saw Jooste walking towards him he thought he was a security guard because of his attire, which resembled a camouflage uniform.
"He said please help me, I've had enough. Just phone the police," Klink said. Jooste also handed his firearm to Klink and asked him to be careful because it was loaded.
Jooste had been on the run since Sunday, after his wife Elmine, his children Blake and Sanjay, his sisters-in-law Sophia Swarts, Janitta Jacobs and Cornelia Visagie, and Sophia's husband Barend, were shot in the head at a farm in Prince Alfred Hamlet, about 200km east of Cape Town.
He fled into a gorge near the farm after the shooting at about 7am on Sunday and was not detected until handing himself him over to Klink on Monday at about 11am.
"I took him to my office and told him to just sit quietly because I didn't want to cause a disturbance," Klink told Sapa.
"He seemed calm but emotionally exhausted."
Jooste was arrested by police from the Op Die Berg police station and taken to the station at Prince Alfred Hamlet.
The explosion of rage in the tranquil community of fruit farmers left people stunned and searching for an explanation.
Farm workers who knew Jooste said he never appeared to be a violent man but had on occasions told people of his marriage difficulties.
"He once told me he had a big problem but did not want to discuss it. He said he would take care of it in his own way," said Basie Jacobs, who works at Ou Muur farm.
The overriding reasons offered by most members of the community were marital problems, but Jooste was also known to be aggrieved after being dismissed from his job as a security guard on the estate after he pointed a firearm at a fellow employee. - Sapa