The DCI revealed the case was escalated to the special unit.
Nyong'o blamed Ruto for deteriorating devolution in a hard-hitting letter.
According to the medical report, the woman suffered soft tissue injuries.
Vocalist and activist Hussein Khalid condemned the incident and demanded an investigation.
The project is linked to another Ksh300 billion project in Western Australia.
The former prime minister has found himself caught up in the news surrounding the death of Pope Francis.
The media house has been grappling with a cash crunch for years now.
It is now uncertain whether the US will heed its initial promise of funding the mission to the end.
The issue has been especially thorny after calls for one-man-one-shilling re-emerged last year.
The governor was critical of the president after Ruto's statement on Sunday.