The staff have been implicated in irregular tendering.
Detectives have arrested three Nairobi County staff over conspiracy to steal Sh997,926 from the Assembly.
Mr Fredrick Mwangi (Senior Finance and Planning Officer), Mr James Kariuki Kaguma (senior procurement officer) and Ms Adah Onyango (Assembly Deputy Clerk) were apprehended on Friday by Directorate of Criminal Investigation (DCI) officers at the Assembly precincts.
The incident comes after Director of Public Prosecutions Noordin Haji ordered the arrest of five county assembly staff who have been implicated in irregular award of tenders and payments at the Assembly, and the proprietor of the company that did business with the Assembly.
Those yet to be arrested are Mr Jacob Ngwele (Assembly Clerk), Mr Raphael Mwinzi Maluki (owner of Primara Ventures) and Ms Philomena Nzuki (Principal Accountant).
Mr Haji said that the DCI initiated the investigations after receiving the County Assembly's internal audit report for the 2016/2017 financial year.
He said the report revealed that Primara Ventures was irregularly awarded a tender for the supply of books worth Sh997,926 to the Nairobi County Assembly Resource Center.
He said the money was paid on June 29, 2017 yet no books were supplied.
He also said the tender was never advertised and the quotations used were wrongly prepared by procurement officers attached to the Assembly.
"I have independently reviewed the file and I am satisfied that the persons named herein actively participated in the perpetration of the alleged criminal activities and should therefore be charged and prosecuted," Mr Haji said.