Opposition chief Raila Odinga has said he will move to court to challenge the formation of a commission of inquiry into the Shakohola deaths.
He said investigations into the massacre cannot be done by a government whose officers are believed to be accomplices in the mass killings.
Raila added that it is unconstitutional for President William Ruto to appoint a judicial commission of inquiry to look into the matter.
"Tangu 2010 Katiba mpya, Rais hana uwezo wa kuunda jopokazi la kufanya uchunguzi. Hio imewekwa chini ya Bunge (Since the 2010 Constitution, the President has no powers to form an inquiry. That is the duty of the Parliament)," he said.
The Azimio leader spoke on Saturday during a burial ceremony in Chonyi, Kilifi County.
Raila accused the National Assembly of neglecting its mandate as far as investigations into the Shakahola tragedy is concerned.
"I will go to the court to report that the appointment of the commission goes against our Constitution," he said.
The former Prime Minister reiterated his belief that the government has something it's hiding in relation to the probe into the Shakahola cult, saying those appointed would be subjective.
"He (Ruto) wants to bury this scandal. That is why he has appointed that inquiry commission and named his friends so that they can file the report that he wants."
Raila added that Kenyans want the truth concerning what happened as proof that they are being protected against harmful religious practices.
The President derives his powers to appoint commissioners of an inquiry under the Commissions of Inquiry Act.
It states that the President, whenever he considers it advisable so to do, may issue a commission under this Act appointing a commissioner or commissioners and authorizing him or them, or any specified quorum of them, to inquire into the conduct of any public officer or the conduct or management of any public body, or into any matter into which an inquiry would, in the opinion of the President, be in the public interest.
Ruto constituted the eight-member Commission last Friday and named Lady Justice Jessie Lessit as chair.
Members are Lady Justice Mary Kasango, Eric Gumbo, Bishop Catherine Mutua, Jonathan Lodompui, Frank Njenga, Wanyama Musiambu and Albert Musasia.
Oliver Karori and Rachel Maina are the joint secretaries to the Commission.
Ruto named Kioko Kilukumi as lead counsel and Vivian Nyambeki and Bahati Mwamuye as his assistants.
Ruto said the Commission's main mandate is to inquire into the deaths, torture and inhumane and degrading treatment of members of the Good News International Church.
"The team will establish the circumstances under which the deaths and inhumane torture occurred," he said in gazette notice.
The Commission will also seek to establish factors that lead to the rise of the religious extremist institution and other formations that fosters negative religion-based activities.
At least 112 bodies have been exhumed from Shakahola forest since the discovery of the first bodies became public in mid April.