Skip to main content
Find a Lawyer
Please enter a legal issue and/or a location
Begin typing to search, use arrow keys to navigate, use enter to select

Missouri First-Degree Murder

First degree murder is the most serious of the homicide crimes in Missouri. In order to prove that the defendant committed first degree murder, the prosecutor must show beyond a reasonable doubt that the defendant intentionally and deliberately killed a person without a legally justified reason (such as a police officer shooting an armed bank robber with hostages). Serial murderers who kill for fun and individuals who plot and execute a revenge killing of someone who allegedly slighted them would both be examples of first-degree murder.

Missouri first degree murder laws treat the offense as a very serious crime. The penalties are based on the circumstances of the crime. If the criteria for first degree murder isn't met, the defendant may still be found guilty of a lesser murder charge, such as: second degree murder (killing without premeditation), voluntary manslaughter ("heat of passion murder"), or involuntary manslaughter (an accidental killing).

Defenses to Murder Charges

Some defenses to first degree murder are complete, meaning the person walks free if believed by the court. For example, innocence is a complete defense, as potentially lack of intent or lack of knowledge could be. However, others defenses, such as self-defense, insanity, or intoxication are often only partial. Partial defenses may only reduce the crime to a lower murder charge, such as manslaughter.

Penalties and Sentences

Missouri law permits capital punishment, or the death penalty. A capital murder case is bifurcated. First, the issue of guilt is determined. Then a second phase of the trial on sentencing begins. At the sentencing hearing, the judge or jury hears evidence on both aggravating and mitigating factors involved in the crime and issues a penalty, including death, based on those factors. Aggravating circumstances show maliciousness, insult, lack of remorse, etc. and increase penalties, while mitigating circumstances decrease criminal responsibility or bear on why the crime was committed (such as years of abuse at hands of the murder victim), thereby making a less severe sentence reasonable.

Missouri law dictates what can be considered as aggravating and mitigating factors. The aggravating factors that can be presented by the prosecutor are:

  • The murder was committed:
    • In an outrageous, vile, or depraved manner or involved torture
    • While committing or attempting another homicide
    • While creating a significant risk of death to more than one person because of the weapon or device used (i.e. a bomb)
    • For money (i.e. paid hitman or kills spouse for life insurance funds)
    • While committing or attempting rape, sodomy, burglary, robbery, kidnapping, or a felony drug offense
    • To conceal a drug-related felony offense
    • To avoid arrest
    • To stop a person from aiding in a drug felony offense prosecution
    • During the commission of a "criminal street gang activity" crime
  • The victim was:
    • A judge, prosecutor, peace officer, or elected official
    • A police officer or fireman in the line of duty
    • A corrections employee or an inmate
    • Killed because he or she witness in an investigation or prosecution
    • Killed due to a hijacking
  • The defendant:
    • Had prior murder or serious assault convictions
    • Directed another to commit the murder or committed murder for another
    • Was escaping jail or prison when he or she killed the victim

The mitigating circumstances that can be considered are:

  • That the defendant:
    • Has no significant history of prior criminal activity
    • Was a minor accomplice to a murder committed by another
    • Acted under extreme duress or under the control of another
    • Lacked the capacity to appreciate his or her conduct and the law
    • Was young at the time of the crime
    • Was under extreme mental or emotional disturbance
  • That the victim:
    • Consented or participated in the defendant's act

Missouri First Degree Murder Laws: Statute

The following table highlights the main provisions of Missouri's first degree murder law.

Code Sections

Missouri Revised Statutes Section 565.020

What is Prohibited?

A person commits murder in the first degree if he or she knowingly causes the death of another person after thinking about doing it.


Murder in the first degree is punishable by the death penalty or life imprisonment without the possibility of parole.

Exception: Defendants who commit any murder before they are 18 years old can't be sentenced to death.

Civil Case

The family of a murder victim can sue the killer for wrongful death, whether or not he or she was convicted of the crime. Famously, this happened with O.J. Simpson, who was not convicted of murder, but did lose his wrongful death lawsuit. If you're sued for wrongful death, you should consult with an experienced personal injury defense attorney.

Note: State laws are constantly changing -- it's important to verify the state law(s) you are researching.

Handling a murder charge is a very serious undertaking. If you find yourself facing any murder or manslaughter charge, you should contact an experienced Missouri criminal defense attorney or public defender for assistance.

Research the Law

Missouri Involuntary Manslaughter Laws: Related Resources

Was this helpful?

You Don’t Have To Solve This on Your Own – Get a Lawyer’s Help

Meeting with a lawyer can help you understand your options and how to best protect your rights. Visit our attorney directory to find a lawyer near you who can help.

Or contact an attorney near you:

Next Steps: Search for a Local Attorney

Contact a qualified attorney.

Begin typing to search, use arrow keys to navigate, use enter to select

Can I Solve This on My Own or Do I Need an Attorney?

  • Complex criminal defense situations usually require a lawyer
  • Defense attorneys can help protect your rights
  • A lawyer can seek to reduce or eliminate criminal penalties

Get tailored advice and ask your legal questions. Many Missouri attorneys offer free consultations.


 If you need an attorney, find one right now.

Copied to clipboard

Find a Lawyer

More Options