The 41-year-old Poonyane was gunned down while on duty in Vierfontein last week.
It is alleged that on February 11 Poonyane and his colleague, Sergeant Lydia Tladi, 45, were on duty when they spotted a Ford Bantam bakkie with two suspicious occupants.
The officers, who were travelling in a marked police van, followed the bakkie as far as Orkney.
Police spokesperson Brigadier Vishnu Naidoo earlier said the two officers had approached the bakkie on foot after the driver brought it to a halt at a stop sign.
“The occupants also got out of their vehicle and denied the police the opportunity to search their vehicle. An argument ensued, resulting in the suspects allegedly shooting both SAPS members,” said Naidoo.
Poonyane died after being shot in the chest, while Tladi was wounded in her leg.
The gunmen fled with the officers’ service pistols and ammunition.
Following the incident, national police commissioner General Khehla Sitole activated a team from the North West Organised Crime Unit, Klerksdorp Trio Crime Unit, national and provincial crime intelligence units, as well as a tactical response team, to trace the suspects.
Two suspects were arrested within 48 hours of the shooting.