Skip to main content

Man Pleads Guilty to Murder After Body of Girl, 4, is Found Covered in Bruises and Blisters from Beatings to Exorcise a ‘Demon’

Ethan Mast and Kourtney Aumen via Benton County Sheriff's Office

Ethan Mast and Kourtney Aumen were both charged with murder in the death of Jessica Mast, 4.

A Missouri man has pleaded guilty to the second-degree murder of a 4-year-old child who died in what the Benton County Sheriff’s Office described as a “religious-type episode” to exorcise a “demon.” The guilty plea appeared in online court records reviewed by Law&Crime on Wednesday and Thursday.

Ethan Mast, 36, had been facing charges including first-degree murder, abuse of a child, child endangerment, assault, and armed criminal action, according to Benton County court documents.  However, Mast on Tuesday entered guilty pleas to a single count of second-degree murder and a single count of first-degree or attempted assault involving serious physical injury or a special victim, according to those records.

It’s unclear whether the admission to a lesser murder count might offer the defendant any relief at sentencing.  Under Missouri law, second-degree murder is a Class A felony.  Class A felonies are generally punishable by life in prison or a term of “twenty years or more.”  Plus, the law states that any sentence attached to the assault charge must be served back-to-back — or in addition to — the murder sentence.

When contacted by Law&Crime, the prosecutor’s office pointed all questions about the case toward the available court record.

In Missouri, second-degree murder is, in essence, a felony murder rule.  It allows prosecutors to allege murder where a defendant commits an underlying felony and, in connection with that underlying felony, a person dies.

Court records show during his appearance on Tuesday, Ethan waived his right to a preliminary hearing and signed a plea deal, the precise contours of which are still unknown. None of the other charges Ethan had been facing have been updated in his record.

The written waiver and plea agreement were submitted to the court by Katherine Dolan, the court record indicates. She is the director of the sexually violent predator unit of the Missouri Attorney General’s Office and serves a dual role with the U.S. Attorney’s Office.

Ethan is one of four adults reportedly charged by the Benton County Prosecuting Attorney’s Office in the death of Jessica Mast, a 4-year-old girl found dead on the floor of her bedroom.  A deputy found the little girl after responding to a 911 call from James Mast, 29, the girl’s father, in December 2020, according to a criminal complaint filed by assistant prosecuting attorney Rodney E. Richardson. Though Ethan Mast shares the same last name as the victim and her father, authorities do not believe they are related, the complaint indicates.

The deputy who responded to the call alleged as follows, according to court papers:

I responded upstairs and walked through the bedroom door at the top of the stairs. When I opened the door I observed a four-year-old juvenile female [redacted] laying on the floor next to a set of bunkbeds wrapped in a pink blanket. I reach[ed] down and found the female lifeless, her eyes partially open, her skin was cool to the touch. James had followed me upstairs and advised that he covered her with a blanket after he found her. I removed the blanket and observed severe purple bruising from the child’s neck to her feet on the front and back sides. I also observed open wounds on the back of her legs that appeared to be from blisters rupturing. I observed the victim’s hair was wet with ponytail bands in it. I observed there appeared to be vomit near the victim’s head. I observed much of the bruising on the victim’s body had what appeared to be signature belt marks all over.

The responding deputy then asked James what happened to the girl.  The complaint document continues:

James said the neighbors came into his house and beat [redacted]. James then told me he had video of the neighbors coming into his house, but after they enter they shut down the home’s interior surveillance system every time they come in. James told me the neighbors got his belt and be[at] [redacted] up. I asked James if he was home during the beating and he said he was, and that the suspects made him watch them commit to crime. James said [redacted] tried to run to him for help, then hesitated and said, “It was the craziest thing.” James then told me it was not the first time this has happened. I then observed James appear to be somewhat distraught and then he told me he didn’t know what to do. I asked James where the belt was and he stated it was downstairs in the bedroom. James stated the suspects went into his bedroom and got the belt to do the beatings. I asked James if the suspects just walked into his home. James responded by saying that they’ve been coming over on a regular basis harassing them. I asked James where his wife was, he stated that she was down the hallway with the infant and 11-month-old.

According to court documents, James Mast then told the responding deputy that the neighbors in question were Ethan Mast and Kourtney Aumen, 22.  The father asserted that Ethan Mast was not related to him.

James and Mary Mast, the victim's parents, are also facing charges surrounding the death of their daughter.

James and Mary Mast, the victim’s parents, are also facing charges surrounding the death of their daughter.

When asked by the responding deputy to detail the events of that day, the criminal complaint says James was somewhat vague, so Mary Mast, 30, was asked to detail what happened to her daughter. Mary allegedly told the responding deputy that both she and her daughter were viewed as “demons” who required routine beatings.  She then is said to have described what she claims happened to her daughter just hours prior.  Again, from the court records at lenth:

Mary said Ethan and Kourtney seen on the camera that [redacted] was fussing so they beat her again with a belt. Mary said they told [redacted] she had to lay still on her stomach. I asked Mary what time that beating happened and she stated it was about 6pm, or maybe 5pm. Mary said that they beat [redacted] and the point was for her to lay still and accept it. Mary said [redacted] was not going to do that without extreme, and he (Ethan) was hitting her really hard with the belt. Mary said [redacted] tried to run to James. I asked Mary where James was and Mary said in the room watching. The suspects told James if he does anything that the suspects would start hitting him. Mary said the suspects said they wouldn’t do this to a little girl, they would only do this to a “Demon” because [redacted] was like her.

Mary went on to say Ethan and Kourtney wouldn’t let James get [redacted] when she ran to him. Mary said the suspects pulled [redacted] away from James. Mary said the suspects told her the same as they did James, (not to help the child), and that one time she (Mary) couldn’t get away fast enough and [redacted] grabbed her dress. Mary stated “It’s hard when you try to run away from your little girl.”

I asked [redacted] what else happened to [redacted] on this night. Mary said after the beating the suspects made her take [redacted] out to the pond, and she had to dip her in the pond. Mary said she then had to lay [redacted] on the shore while she was forced to swim around the pond until they told her she could come back. Mary said she was also forced to dip into the water before she could bring [redacted] into the house. Mary said it wasn’t the first time she had to get into the pond.

I asked Mary why [redacted] was naked. Mary said Ethan and Kourtney told her they couldn’t do anything for [redacted] or put any clothing on her, and they would make her undress also and go into the pond. I asked how [redacted] got into her room, and Mary said James carried her to her room. I asked if [redacted] was alive and Mary stated she was. Mary said James was very concerned about [redacted].

Mary stated when [redacted] was downstairs, Ethan and Kourtney tried to get [redacted] to stand up, but she wouldn’t (couldn’t). Mary said Ethan and Kourtney hit [redacted] a few more times, but she still wouldn’t stand up. I asked Mary what they hit [redacted] with when she would stand up and she stated “It was the belt again to try and get her to respond”. Mary said the suspects then said “Just get her out of here”, at which time James was allowed to take [redacted] to her bedroom. Mary said James carried [redacted] up to her bedroom and put her in bed naked.

The Benton County Sheriff’s Office decided to arrest Ethan and Kourtney that day “pending multiple felony charges.” Mary and her 2-year-old son meanwhile were “transported by ambulance” to a local hospital because they had been “beaten to a severe extent,” according to a Sheriff’s Office press release.

Four days later, on Christmas Eve, the Benton County Sheriff’s Office announced on Facebook that the parents had also been arrested:

Mary is being charged with Endangering the Welfare of a Child in the First Degree Resulting in Death (Felony A) and Domestic Assault in the First Degree (Felony A). James is being charged with Endangering the Welfare of a child in the First Degree Resulting in Death (Felony A) and Endangering the Welfare of a Child in the First Degree Resulting in Serious Physical Injury (Felony B) Both individuals are being held without bond, the Mast’s two-year-old son and infant son have been placed in protective custody.

Law&Crime previously noted that James and Mary petitioned the court to attend their daughter’s funeral a few days after their arrest, but a judge denied that request.

Ethan’s case is the first to be adjudicated by way of his guilty pleas. James and Mary are facing second-degree murder charges in addition to counts of abuse, child endangerment, and assault, according to court documents filed in Benton County Circuit Court. Kourtney had been facing the same charges but successfully petitioned to have her case transferred to Webster County in January, court records indicate. A full list of the charges she faces is not included in an online Missouri court portal for either her Benton County case or her Webster County case.

Read some of the court documents below:

[All images via Benton County Sheriff’s Office mugshots.]

Have a tip we should know? [email protected]

Filed Under:

Follow Law&Crime: