Mo. Rev. Stat. § 565.072: Domestic assault, first degree — penalty.

1. A person commits the offense of domestic assault in the first degree if he or she attempts to kill or knowingly causes or attempts to cause great bodily harm to a domestic victim, as the term "domestic victim" is defined under section 565.002.

2. The offense of domestic assault in the first degree is a class B felony unless in the course thereof the person inflicts serious physical injury on the victim, in which case it is a class A felony.