Triple murder trial hinges on mental diagnosis

Verdict against Kavanagh expected on Friday

Adam Rollins, Staff Writer
Posted 3/15/23

In the murder trial of Shawn Kavanagh, very few facts are in dispute. On Valentine’s Day, Feb. 14, 2014, Kavanagh entered a home south of Jonesburg with a knife in his hand. There, he brutally …

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Triple murder trial hinges on mental diagnosis

Verdict against Kavanagh expected on Friday


In the murder trial of Shawn Kavanagh, very few facts are in dispute. On Valentine’s Day, Feb. 14, 2014, Kavanagh entered a home south of Jonesburg with a knife in his hand. There, he brutally murdered a 7-year-old child and two adult women, stabbing and cutting each of them dozens of times. He also stabbed a third woman, his estranged wife, four times, including once in the heart.

Kavanagh’s defense attorneys dispute none of these facts. Instead, the multi-day murder trial that began on Monday this week focused on one main question: Whether Kavanagh had the presence of mind during his rampage to merit the state’s most severe murder charge and a potential death penalty.

Kavanagh, 32, is charged with three counts of first-degree murder, one count of first-degree domestic assault, and several other charges related to the killings of 7-year-old Mason Vandiver, Lexy Vandiver and Tara Fifer, and the severe wounding of Jessica Powell. Kavanagh is being tried in a St. Charles County courtroom.

The facts of the case

This trial is the first time that exhaustive details related to the murders are being released to the public. In court, Warren County Prosecutor Kelly King described Kavanagh as a jealous, controlling man who had been in a volatile marriage with Jessica Powell (then named Jessica Kavanagh) since mid-2013. 

Over that time, Kavanagh grew paranoid that Jessica was having an affair with her coworker, Tara Fifer. Tara’s sister, Haley Roberts, testified that she once overheard Kavanagh threatening to kill Tara over his suspicions.

Kavanagh and Jessica were living in separate homes in early 2014 following a domestic assault; Kavanagh was living with his parents in Bellflower, while Jessica was staying with another coworker, Lexy Vandiver, and her two children, Mason and 18-month-old Jeannette. They lived in a home in Warren County south of Jonesburg.

Despite a court order forbidding contact, Kavanagh and Jessica continued to text each other. They set up plans for Jessica to visit Kavanagh on Valentine’s Day. But as that day went on, texts between the two show that Jessica continually put Kavanagh off, making excuses for why she couldn’t come.

Jessica, the only one of Kavanagh’s victims to survive, testified on Monday that Kavanagh displayed frequent episodes of “blackout” rage. She said she had no intention of visiting him on Valentine’s Day, but she didn’t want to tell him because she feared making him angry. She, Lexy, and Tara were going to the casino, and the three of them were at Lexy’s home getting ready that evening.

Before they could leave, Kavanagh came to the home looking for Jessica. Upon seeing Tara’s truck there, Kavanagh began escalating into a rage and came to the door to find Jessica. After all three women told Kavanagh to leave, he used a knife to begin attacking them.

He first wounded Jessica, then pursued Lexy and Tara into different bedrooms in the home, where he killed them. In the bedroom with Lexy, Kavanagh also fatally wounded Mason. Deputies later asked Kavanagh why he attacked Mason, and he replied “I don’t know — he got in the way,” according to a recording played in court. The boy had dozens of wounds on his body.

Jessica testified Monday that after the killings, as she bled from a wound in her chest, Kavanagh stood over her and asked “how it felt to be stabbed in the heart.” He then became extremely distraught at his own actions, called 911, and surrendered himself to Warren County sheriff’s deputies.

Years of pain

Only two people in the home with Kavanagh lived through that day: Jessica and 18-month-old Jeannette, who was uninjured. A close friend of the victims’ families told The Record on Monday that they are grateful that Jeannette wasn’t old enough to remember the attack.

Jessica testified that she was left with permanent, severe psychological trauma after the attack, along with permanent physical symptoms of her injuries and the surgeries required to save her life. She said she developed auto-immune disorders as a result of blood transfusions during her treatment. But she’s also tormented by the memory of what was done to her friends.

“I can’t stop thinking about the other families, how hurt they must be. I feel horrid, because they were such great people,” she said.

Testimony on Monday also revealed that the brutality involved in Kavanagh’s attack also left mental scars on the sheriff’s deputies who responded to the home. Multiple current and former deputies took the stand Monday, and several became distraught when asked to recall details of the killings. That was particularly true for details involving the child, Mason, who was found alive with severe injuries after the attack and later died at a hospital. 

At one point, Lt. Detective Scott Schoenfeld was asked to verify the authenticity of several photos so that they could be entered into evidence. No one else in the court could see the photos, but Schoenfeld became visibly distressed as he looked through them. He ground his teeth and held back tears as he examined each photo, before handing them back to prosecutor Kelly King.

“Can you tell the court what these are?” King asked. Schoenfeld covered his mouth and composed himself for a long time, before apologizing and answering that they were autopsy photos of Mason’s injuries.

Throughout this week’s trial, family members of the victims have sat stoicly in the gallery of the courtroom, viewing photo evidence of the violence and bodies that Kavanagh left in his wake, and listening to recordings of Kavanagh’s interrogations after his arrest. These families have waited through nine years of delays in order to see the trial happening this week.

The defense

Kavanagh’s attorneys from the Missouri Public Defender System don’t dispute any of the major facts of this case. In fact, they fully acknowledged in their opening statement that Kavanagh is guilty of murder.

The sole focus of the defense attorneys is on one goal: Showing that Kavanagh’s actions lacked the element of deliberation that is necessary for a first-degree murder conviction and a possible death sentence. Instead, the defense attorneys asked Judge Rebeca Navarro-McKelvey to convict Kavanagh of second-degree murder.

On Tuesday, the defense asked two clinical psychiatrists to testify that Kavanagh suffers from multiple mental defects, most relevantly including Intermittent Explosive Disorder and Borderline Personality Disorder. These conditions would cause him to become irrationally angry and incapable of the sort of deliberation or “cool reflection” required for a first-degree murder conviction, the doctors testified.

One of the psychiatrists, Dr. Bruce Harry, a retired two-decade employee of the Missouri Psychiatric Hospital in Fulton, said records collected from throughout Kavanagh’s life strongly indicated these mental disorders long before the attack on Feb. 14, 2014.

Dr. Harry testified that on the night of the attack, from the point that Kavanagh experienced the trigger condition of seeing Tara Fifer’s truck outside the home, he likely experienced a paranoid rage and was incapable of calm reflection.

Prosecutor King has been pushing back on that conclusion, stating that details of the attack show that Kavanagh had intent; that he was particularly violent in his killing of Tara, who he thought was having an affair with his wife, while he also specifically wounded Jessica in the heart.

The hearings to determine what crime Kavanagh is guilty of were set to continue on Wednesday, with Judge Navarro-McKelvey expected to announce a verdict on Friday. Check for the latest updates.

Sentencing hearings for Kavanagh are scheduled to take place next week.

Shawn Kavanagh, Murder, Assault, Trial