Public Service Principal Secretary Lillian Mbogo-Omollo and National Youth Service (NYS) boss Richard Ndubai are among 29 government officials who could be arrested after they were questioned by police.
Others include a chief accountant, head of procurement, principal accountant, head of accounts and the financial and economic officer at NYS.
Treasury officials are also facing arrest after police narrowed down to questionable payments paid through the Integrated Financial Management Information System.
Fourteen directors of 10 companies that did business with the NYS were also interrogated by police detectives.
The Director of Criminal Investigations, Mr George Kinoti, said: “Of all those whose statements were recorded, we are preparing to make at least 30 arrests. They will have their day in court and none will be spared, irrespective of their rank. Public money was stolen and the suspects must be charged.”
Mr Kinoti, who spoke to the Nation on Tuesday, said he expected the arrests to begin within 36 hours.
The DCI on Monday began questioning the officials and recording their accounts on the loss of Sh9 billion paid out in questionable contracts.
In a long list of companies under investigation, two —Firstling Supplies and Flagstone Merchants — received Sh 1.7 billion from the National Youth Service between November and December last year.
Some of the transactions under investigation were double payments.
In one case, four payments were made to a company for one voucher. Each of the payments was worth more than Sh46 million, with the difference in amounts varying by only a few hundreds of shillings.
In another such payment, the company received equal amounts of money, yet only one voucher was available for scrutiny.
Detectives are struggling to establish whether the deliveries indicated were even made.
Multiple payments were released from the IFMIS to the companies’ accounts at intervals, with the amounts being released less than an hour after a claim was made.
Meanwhile, the Public Accounts Committee has summoned Public Service Cabinet Secretary Margaret Kobia and her predecessor, Ms Sicily Kariuki, over the scandal.
The order to summon the two CSs and other top ministry officials came after Ms Omollo and Mr Ndubai failed to show up before the committee to answer to audit queries by the the Auditor-General, Mr Edward Ouko, for the financial years 2014/2015 and 2015/2016.
The committee’s Chairman and Ugunja MP Opiyo Wandayi said Ms Omollo and Mr Ndubai must appear before the team on Friday this week.
They are expected to appear alongside Ms Omollo, Mr Ndubai and all other affected officers in the ministry.
The PS and the NYS director-general were forced to step aside for three months to allow the detectives to finish the investigation.
Other officers from the procurement, finance and accounts department were sent on compulsory leave on Sunday by Prof Kobia.