Police have been instructed to investigate the man who allegedly supplied the murder weapon used to kill music icon Taliep Petersen.

This has been confirmed by National Prosecuting Authority (NPA) spokesperson Sandy Godlwana.

However, she said there was not enough evidence against the man, Sedick Kriel, in order to make an arrest.

Godlwana said the only evidence against Kriel was the confession in which hitman, Waheed Hassen, implicated Kriel as the man who supplied the firearm.

Once investigated further, and if sufficient evidence was obtained, the matter would be referred to the NPA.

The investigation of Kriel follows comments by Justice Siraj Desai during the sentencing of Petersen's widow Najwa and her three co-convicted in the Cape High Court on Wednesday.

He said the court had never been told why Kriel had not been prosecuted and urged police to take the matter further.

Kriel's name was first mentioned in the trial by Hassen, who testified that he had fetch-ed the firearm from Kriel's home just before the murder.

Afterwards, he and Jefferson Snyders drove back to Kriel to return the firearm. He had noticed that the slide of the gun was still slightly open and that the shell of the cartridge had not been expelled from the loading chamber.

He said he had removed it from the chamber and, in frustration, because he did not intend killing someone, he started chewing the shell. Later he spat it out of the window.

The firearm was never recovered.

Petersen was convicted of murder after the court found that she had masterminded her husband's December 2006 killing.

Hassen and Abdoer Raasiet Emjedi were also convicted of the murder. The three, as well as Snyders, were also convicted of robbery with aggravating circumstances.

The court acquitted Snyders of the murder after finding that he had disassociated himself from the murder.

Petersen was sentenced to 28 years for the murder while Emjedi and Hassen were each sentenced to 24 years on that charge.

The court imposed an additional one-year sentence on Hassen for the unlawful possession of a firearm.