Police released an identikit of the man on Thursday.
“The suspect is in his early 30s, not older than 34, [of] slight build, 1.7m tall, light in complexion, and was wearing a wool hat,” Lt-Col Lungelo Dlamini said.
“It is believed that he has different colour wool hats. He has a cut on the lower lip and a red ring on his left hand. He is believed to be either from KwaZulu-Natal or Swaziland.”
Four foreign nationals were taken in for questioning.
The bodies of two-year-old Yonelisa Mali and her cousin Zandile Mali, three, were found in a public toilet cubicle in Diepsloot at 5am on Tuesday by a resident.
They were reported missing at the weekend.
Residents went on the rampage after the bodies were discovered.
Police said a team of detectives had been appointed to investigate the murders. – Sapa