Section 215.13. Tampering with a witness in the first degree

A  person  is  guilty  of tampering with a witness in the first degree
  when:
    1. He intentionally causes serious physical injury to a person for the
  purpose of obstructing, delaying, preventing or impeding the  giving  of
  testimony  in  a criminal proceeding by such person or another person or
  for the purpose of compelling such person or  another  person  to  swear
  falsely; or
    2.  He  intentionally  causes  serious  physical injury to a person on
  account of such person or another person having testified in a  criminal
  proceeding.
    Tampering with a witness in the first degree is a class B felony.