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.