Detective constable Stephen Adams told Research that the men, 22-year-old Elton Smith and 23-year-old Wayne Smith, both of Eerste River, Cape Town, will remain in custody until the trial, which is set to begin later this month.

Jonkheid, the founder of Johannesburg-based research agency The Consumer Psychology Lab, was found dead in the town of Stellenbosch, near Cape Town, on 30 May, after attending the South African Marketing Research Association’s annual conference.

He was reported missing by his wife after failing to arrive for his flight back home, and his body was later found partially burnt and with a gunshot wound to the head.

Police said the men were found with Jonkheid’s cellphone as well as the spare wheel, battery and radio from the car he had rented.