Elizabeth McKeown (Greene County Jail)


The attorney for a Greene County murder suspect says some over-the-counter cough syrups can cause psychotic behavior in certain individuals and that his client’s use of cough syrup might play a role in her June 6 trial.

Elizabeth McKeown, who is 49 or 50 years old, is accused of deliberately running over and killing a stranger to her, Barbara Foster, of Springfield, on Nov. 20, 2018.

The Springfield Daily Citizen reported April 25 on the upcoming trial, but did not hear back from defense attorney Jon Van Arkel until late in the day.

In an email to me, Van Arkel wrote:

“This case will likely present issues regarding pre-existing mental health circumstances, as well as blood chemistry, which may have resulted in psychotic behavior at the time of the incident.”

It appears it is a rare legal argument that a defendant’s mental capacity can be diminished by a psychosis caused by the inability to metabolize dextromethorphan, the key ingredient in some cough syrups.

The April 25 column noted that, according to online court documents, McKeown — while in custody in July 2021 — was to be tested to “determine liver function and the ability to metabolize dextromethorphan.”

While that test, if performed, would have been done almost three years after McKeown allegedly ran over Foster, the purpose would have been to determine how well McKeown’s body metabolizes the drug and how quickly it gets it out of her system.


“As a side note,” Van Arkel wrote in his email, “and as you have already surmised, a chemical constituent of some over-the-counter cough syrups can cause psychotic behavior in certain individuals if they do not (their liver does not) metabolize DMX and those levels are elevated. Not sure why the companies that manufacture cough syrup are allowed to get away with that, but that is a bigger policy issue and beyond this case.”

Van Arkel said he could not go further into the details of the case.

“As much as I appreciate your inquiry, I am not at liberty to disclose or discuss the facts of this particular case. On the other hand, I realize the circumstances of this case is of interest to your readers and to the community as it has a strong human-interest component.

“Ms. McKeown’s plea of not guilty by reason of mental disease or defect is a matter of public record. Whether Ms. McKeown suffered from psychosis and from what source that psychosis arose would likely be an issue in this case at trial.

“Hypothetically, as is true under Missouri law for all criminal defendants, if a person substantially suffers from a mental disease or defect/psychosis then perhaps they may not be criminally responsible for their actions, even though they may then possibly for the duration of their lifetimes come within the care and custody of the Missouri Dept. of Mental Health.”

McKeown allegedly told police she got upset sitting in afternoon rush-hour traffic behind Foster’s vehicle — at Campbell Avenue near University Street— because she was in a hurry to get to the bank to make a car payment.

A probable cause statement says McKeown told police that when Foster “wouldn’t go,” she started nudging Foster’s car and then “decided to hit it full out.”

Prosecutors have described McKeown’s actions as “road rage.”

After the impact, the probable cause statement says, Foster got out of her car to assess the damage, and McKeown hit Foster with her Ford Mustang.

After hitting Foster, police say McKeown was involved in another crash a couple of blocks away at the intersection of Campbell and Sunshine Street. It’s there that authorities say witnesses helped box in McKeown’s car before police arrived.

Foster was 57; she worked at Eyeglass World.

Emily Shook, a Greene County prosecutor in the case, said she does not know how rare a defense involving cough syrup would be.

Murder defendant was once a nurse

The Springfield News-Leader reported soon after the death that McKeown is a former nurse, a wife, a mother, a real estate company employee and someone who struggled with bills and drugs.

Court documents say McKeown worked at Family Home Solutions of Southwest Missouri, a real estate company, but her background is in nursing, according to the newspaper.

In Arkansas, where McKeown lived before moving to Missouri, she worked at St. Edward’s Mercy Medical Center in Fort Smith, but she was fired in 2006, according to the newspaper.

Fred Knight, general counsel for the Arkansas State Board of Nursing, told the newspaper that McKeown’s nursing license was suspended after she was twice caught stealing Nubain, a prescription painkiller, in August 2006.

Knight said McKeown took the drugs out of the hospital’s internal system but never gave the drugs to the patient. McKeown admitted to using the drugs herself, Knight told the News-Leader.

Court documents also detail a string of money problems McKeown encountered in the decade prior to Foster’s death.

In Missouri, first-degree murder is punishable by either life in prison without the possibility of parole or the death penalty. Shook said the state is not seeking the death penalty in this case.

McKeown is being held in the Greene County Jail without bond.

According to the National Library of Medicine:
Dextromethorphan might cause side effects that include dizziness, lightheadedness, drowsiness, nervousness, restlessness, nausea, vomiting and stomach pain.

Symptoms of overdose might include hallucinations, nausea, vomiting, drowsiness, dizziness, unsteadiness, changes in vision, difficulty breathing, fast heartbeat, seizures and coma.

This is Pokin Around column No. 32.

Steve Pokin

Steve Pokin writes the Pokin Around and The Answer Man columns for the Springfield Daily Citizen. He also writes about criminal justice issues. He can be reached at spokin@sgfcitizen.org. His office line is 417-837-3661. More by Steve Pokin