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What does Missouri law say about first-degree murder?

On Behalf of | Jun 28, 2022 | Criminal Defense |

Of all the forms of homicide for which you can face prosecution in Missouri, first-degree murder is the most serious. As FindLaw explains, Missouri law categorizes first-degree murder as a Class A felony. If convicted, you could face the death penalty or, at best, life in prison without any possibility of parole.

To convict you of first-degree murder, however, the prosecutor must prove that you deliberately and intentionally killed someone for no justifiable reason after contemplating your actions ahead of time.

Aggravated circumstances

In addition to “regular” first-degree murder, Missouri law also provides for first-degree murder with aggravating circumstances, conviction of which almost assures the death penalty. Aggravating circumstances include the following:

  • You murdered your victim during the commission of a serious crime, such as kidnapping, robbery, burglary, rape or sodomy.
  • You murdered him or her while participating in criminal street gang activity.
  • Your victim was a judge, prosecutor, elected official, firefighter, police officer or corrections officer who was acting in his or her official capacity at the time of the murder; alternatively, he or she was a prison inmate at the time of the murder.


Complete defenses that could result in your acquittal include the following:

  • Innocence
  • Lack of knowledge of the murder
  • Lack of intent to commit murder

Incomplete defenses that could result in a reduction of your sentence upon conviction, include the following:

  • Insanity, i.e., lack of mental capacity to appreciate the nature of your action or the law against it
  • Acting while under extreme duress
  • Consent on the part of the victim; for example, assisted suicide

Keep in mind that, even if a jury acquits you, the victim’s family can nevertheless bring an action for wrongful death against you in civil court.