The father of Skierlik murderer Johan Nel may be recharged with the negligent handling of a firearm, police said on Monday.

Superintendent Lesego Metsi said the charge had been withdrawn in the Swartruggens Magistrate's Court for unknown reasons.

"The investigating officer said to me they have already referred an application for review to the directorate of public prosecutions," said Metsi.

He said the father, Hennie Nel, was responsible by law to safeguard his firearm. The rifle, which was used in his son's shooting spree that killed four people, was not locked in a safe at the time of the attack.

Initially, a charge of negligent handling of a firearm was brought against the father.

"But the court withdrew the charges for reasons that are not clear."

If convicted, the father's firearm licence could be revoked for five years, said Metsi.

Nel was last week sentenced to four life terms for the shooting spree in which he killed four people, including two children, and wounded eight people at the Skierlik informal settlement, near Swartruggens, on 14 January.