The state has dropped charges against Esther Nthenya Muli, a secondary teacher who had been accused of attempted murder of Machakos Senator Boniface Kabaka.
On Thursday the prosecution said after analyzing report from the government chemist, could not find sufficient evidence to hold her.
In December 2020, tests conducted on the senator ruled out the possibility that he could have been poisoned, as earlier thought.
The leadership of Makueni County came to the defence of Nthenya who was arrested after the late Machakos Senator was hospitalised following a sudden illness.
Makueni Governor Kivutha Kibwana described Esther Nthenya Muli as a "caring lady" while Makueni MP Daniel Maanzo, who is her lawyer, said she was a "harmless woman of repute caught up in issues she had nothing to do with".
"A caring lady (from Makueni) who takes a gentleman in distress to the hospital cannot be a murderer. She deserves bail and justice," Prof Kibwana posted on social media.
Ms Muli was held over the sickness of Senator Kabaka but was released on December 10 from Kilimani police cells after 36 hours.