This position of influence turned Matiang'i into the single most powerful individual after former President Uhuru Kenyatta who was his boss and the commander-in-chief.
After President William Ruto was announced winner of the August polls by the IEBC, and his election victory confirmed by the Supreme Court, Dr Matiangi bid farewell to his colleagues and announced that he was leaving office after five years and one month as the CS in charge of security.
"As my tour of duty comes to an end, I exult in the pride of knowing that we have not only honoured expectations but exceeded them by important and evident milestones. History will vindicate our legacy. This has been made possible by working closely with you and other highly experienced, competent and dedicated colleagues in the Public Service.
But since leaving office, things have changed for Matiang'i who has now to endure the wrath of the men and women in uniform whom he was in charge of for over five years as the security boss.
On Friday, Matiang'i was expected at the DCI headquarters on Kiambu Road where he was scheduled to record statements with the police over allegations that the law enforcers had raided his Karen home.
On the night of February 8, former Prime Minister Raila Odinga together with a battery of lawyers rushed to the home of the former CS following claims that there was a plot to raid it.
Now the DCI head of Serious Crime Unit Michael Sang in a letter to the ex-CS on Thursday directed that Matiang'i should present himself before the investigators to shed light on the allegations.
The investigator's letter read in part: "This office is investigating allegations of Publication of False Information contrary to section 23 of the computer Misuse and Cyber Crimes Act 2018 amongst other offences in regard to alleged invasion and raid of your residence (the former Cabinet Secretary, Ministry of Interior and National Co-ordination, Dr Fred Matiangi) on February 8 - 9, 2023 allegedly by a "battalion" and/or "garrison" of police officers."
The ex-CS however did not appear before the DCI investigators as directed and instead sent his lawyer Danson Omari. The lawyer briefed the police that the CS was not in a position to appear yesterday.
Omari said Matiang'i was out of the country and would not therefore be present to record statements. But at the DCI headquarters, some of the investigators we spoke to disputed this, claiming that the former CS was hiding from the police. Former Interior CS Fred Matiang'i during the National Aids Control Council dialogue with Regional Commissioners in Mombasa on April 7, 2022. [Kelvin Karani, Standard]
Last evening, DCI chief Mohammed Amin was expected to issue a directive on the way forward after the former CS failed to honour the summon.
The DCI boss has previously dismissed the claims made by Matiang'i that police officers had raided his home and has demanded that the former CS provides evidence to support the claims.
Amin and Inspector General of Police Japhet Koome in a press statement issued after the claims emerged denied that any police officer had been sent to the home of the ex-cs.
Prof Kindiki Kithure who took over the security docket from Matiang'i issued a statement, short of accusing his predecessor of lying.
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"I sought assurances that we are not taking one step forward and two steps backwards because it's primitive to raid people for nothing," said.
DCI boss Mohamed Amin speaking at the DCI headquarters on the same matter termed the alleged raid by police at Matiang'i's home as "false reports".
"For the record, I can confirm that the DCI is indeed investigating several cases. But I can confirm that none of the cases under investigation so far have reached the stage, which requires the assistance or attendance of Dr Matiang'i," said Amin.
Azimio leader Raila Odinga termed the alleged attempts to arrest Matiang'i oppressive.
"We will not allow the dark days of repression to return. We shall stand with him to the end. He can count on our support and solidarity as Azimio," he said in a statement.
The ex-CS has since moved to the High Court where he sought anticipatory bail over what he feared was a looming arrest.
"Through a confidential source, I was reliably informed that the Ethics and Anti-Corruption Commission had also received instructions between February 6-9, 2023 to open a criminal file and charge me with trumped-up charges of abuse of office," Matiang'i said in court papers.