Director of Public Prosecutions Keriako Tobiko on Tuesday accused Gem MP Jakoyo Midiwo of trying to influence his case through public utterances.
Mr Tobiko also accused Mr Midiwo of personalising attacks against him yet he was only doing his job.
“The matter is scheduled for hearing on May 11. He should be patient and wait to ventilate his arguments in the High Court where the prosecution will also have a chance to state its case,” Mr Tobiko said in a press statement.
“He should allow the legal and due process to take its course,” he added. But Mr Midiwo turned the heat on the DPP, accusing him of “protecting the big boys”.
“Let Mr Tobiko know that we are watching him and we will come after him if he continues protecting the big boys,” said the MP in a telephone interview.
Mr Midiwo said he did not attack Mr Tobiko personally but only criticised "shoddy investigations" into his allegations of an assassination plot against Prime Minister Raila Odinga.
“I did not say anything personal about Tobiko. It’s he who called me a liar over statements on threats against the PM,” he said.
Mr Midiwo made the allegations at a funeral in Bondo on April 7, linking Foreign Affairs minister Sam Ongeri to the plot before recording a statement with the police on April 10 at CID headquarters in Nairobi.
Prof Ongeri denied the claims, terming them as outrageous and threatening to take legal action.
Officers investigating the matter recorded a statement from the Foreign Affairs minister.
Also questioned were Deputy Prime Minister Uhuru Kenyatta, Eldoret North MP William Ruto and Finance minister Njeru Githae.
Police said the politicians were not suspects but were questioned because they had been mentioned by Mr Midiwo.
On April 24, a Nairobi court issued a warrant of arrest against Mr Midiwo days after the DPP recommended he be prosecuted for allegedly giving false information. However, he got a court order barring his arrest. (READ: Arrest of Midiwo stopped)
Speaking to journalists in Kisumu on Tuesday, Mr Midiwo challenged the DPP to prove which part of his statement was false to warrant his arrest, saying he stood by his statement.
“I want Tobiko to tell Kenyans which part of my statement is false and to make public the statements of the people I named,” said Mr Midiwo.
He said he looked at the file Mr Tobiko presented to court and wondered why it was only his statements that had been included yet there were other people who were questioned and who recorded statements over the assassination claim.