Four officials from Nyamira County Assembly and the executive wing are being interrogated at Regional EACC offices in Kisii.
On Friday, two assembly officials were locked up over Sh379 million building after a petition by former Nyamira Senator Okong'o Mong'are.
In his petition, Mr Mong'are accused the assembly of breaching procurement laws.
The project had been launched by speaker Moffat Teya who defended it as 'necessary' for MCAs and the people of Nyamira.
And on Tuesday, two officers were arrested from Roads and Public Works offices over Sh32 million prefab that is supposed to temporarily host county offices.
It is not the first time EACC has raided the department with County Executive Committee member John Omanwa accusing contractors of soiling his name after he blacklisted a few of them.
The two who were arrested were identified as Ben and Oduor working as Physical Planner and Quantity Surveyor respectively.
Currently, they are being grilled in Kisii regional offices over the controversial project.
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