Police were on Wednesday night preparing capital offence charges that attract a death sentence, against Ruaraka MP T J Kajwang'.
The Nairobi News has established that the State will rely on Section 59 and 60 of the Penal Code, which talks about illegal oaths.
TJ Kajwang 'swore' Nasa leader Raila Odinga as the "people's president" at Uhuru Park in Nairobi on Tuesday.
Section 59 says: "any person who is present at, and consents to the administering of, any oath, or engagement in the nature of an oath, purporting to bind the person who takes it to commit any offence punishable with death; or takes any such oath or engagement, not being compelled to do so, is guilty of a felony and is liable to imprisonment for life."
The subsequent section adds: "Any person who administers an oath, or engagement in the nature of an oath, purporting to bind the person who takes it to commit any offence, punishable with death, is guilty of a felony and shall be sentenced to death."
On Wednesday night, Mr Kajwang's supporters camped outside Directorate of Criminal Investigations headquarters on Kimbu Road.
They yelled and sang while demanding for his release.