SIU only gained access to Nkandla last week
The unit is investigating the R246 million upgrades to President Jacob Zuma’s Nkandla homestead.
The unit is investigating the R246 million spent on security u pgrades to the president's private KwaZulu-Natal home.
Earlier this week, the SIU revealed it was still waiting for responses from third parties named in the report.
The unit was initially expected to release its findings to the president in June.
Soni made the comments while answering questions about the delay in the finalisation of the SIU's report during a meeting of Parliament's Portfolio Committee Justice in Cape Town.
He was pressured to name the two people he said were delaying the finalisation of the document.
He says he will have to consider whether to take any action to get the people to respond, as required by law.
Committee chairperson Mathole Motshekga effectively closed down further questioning on Nkandla, despite objections by opposition politicians.
Soni says they're focusing their efforts on catching the big fish behind maladministration and corruption in state departments.
Changes to the SIU's founding legislation means it now has powers to investigate and litigate to recover money stolen through corrupt activity.
The unit's boss says it instituted more than 1,000 civil claims to recover small amounts.
He says the SIU intends launching 20 civil matters dealing with much bigger sums in relation to irregular contracts.