West Pokot County Deputy Governor Robert Komolle is in police custody following arrest by Directorate of Criminal Investigations detectives in Nakuru over alleged incitement.
DCI had summoned Komolle on February 6 for interrogation.
In the letter, Rift Valley Regional Coordinator Charles Kanyuira said they are investigating a case of threatening breach of peace and incitement.
"I have reason to believe that you are either connected with the said offence or have useful information that may assist us in the investigations," read a letter by Kanyuira addressed to Komolle.
The Deputy Governor arrived at the DCI offices at around 10 am, where he was interrogated.
Komolle's lawyer Philip Magal, who addressed the press at around 4:20 pm, confirmed his client had been detained.
Magal said their plea to have him released on police bond was not successful.
"I confirm, indeed, that the Deputy Governor has been arrested. He was summoned to appear before the DCI, and on arrival, his phone was confiscated and fingerprints taken and detained. We have requested that he be released on bond, but our appeal has not been granted," he said.
Magal said on further inquiries, they were informed that the DCI was awaiting orders from above.
And, Tiaty MP William Kamket was released on Thursday.
Kamket was arrested on Wednesday evening by DCI officers and spent the night at Central Police Station.
Addressing the press minutes after his release, the MP said he did not have anything to tell the detectives.
He disclosed that he was released on a free bond and asked to come back after two weeks.
Kamket said he did not know the crime he committed.
"All I know is I have become a foster boy for arrest by the State. When they want to arrest an MP, they come for me. I have never understood why," he said.