Jurors think this daycare provider nearly killed a baby. How she did it, no one could say.

Mariel Grimm

Mariel Grimm Shelly Mosman

The day Mariel Grimm was sentenced for abusing a baby to near death, the Dakota County prosecutor had prepared a biting sermon, demanding this babysitter get nearly five years in prison.

“Mariel Grimm imposed a life sentence on... a baby who cried because he had a soiled diaper,” said County Attorney Heather Pipenhagen, a veteran crusader against crimes targeting children.

“Ms. Grimm asks you for mercy. She showed no mercy on September 22 of last year. For that unforgiveable, irreversible act, she deserves the presumptive guideline sentence. “

Each word was a lashing to the 33-year-old Mariel, a diminutive mother of four. As she sat with her hands clenched in her lap, looking like a kicked dog, it seemed she wanted badly to speak up for herself.

The prosecutor evoked a vision of unthinkable brutality. Yet observers in the gallery were left genuinely wondering what Mariel had actually done. Even by this final stage in her trial, the state could not explain how the baby got his injuries.

The nightmare began on the morning of September 22, 2016, when the 13-month-old woke wailing from a nap.

Shelly Mosman

Shelly Mosman

His cries summoned Mariel, his daycare provider since infancy, whose Eagan home was a lively menagerie of child’s play. In addition to the boy—whom we’ll call Will to protect his privacy—Mariel looked after a church friend’s little girl and her own children, whom she homeschooled.

Will loathed dirty diapers. As Mariel changed him into a new one, she says the little boy suddenly went stiff. His head turned robotically to the right. His right arm flew up into the air. He lost consciousness.

Mariel splashed handfuls of cold water on his face. The baby didn’t wake.

She called Will’s mother, Jessica, in hysterics. Jessica yelled at her to call 911.

On the phone with dispatch, Mariel was barely audible over her mounting panic. She could be heard pleading, “What is happening?” “What should I do?” “Baby, wake up, baby, please.”

Paramedics arrived to discover one of Will’s eyes dilated, the other pinpointed—a sign of critical pressure building inside his head.

When Jessica appeared, Mariel faded into the background as paramedics began to interrogate the mother, trying to uncover any recent injuries that could explain his condition. Will had fallen at least three times at home the day before, Jessica offered.

He’d tripped once. Then he’d fallen backward on the wooden floor while trying to pull an item from the laundry basket. That morning, prior to being dropped off at the babysitter’s house, he’d knocked heads with his father while playing in the pre-dawn darkness of their bed.

Those minor collisions didn’t seem enough to explain his condition. In the hospital, Will moved straight from the CT scanner to the operating room, where a neurosurgeon removed a portion of his skull to relieve the pressure within. He survived.

A child abuse specialist diagnosed him with abusive head trauma. He believed the abuse must have occurred within an hour of the baby’s seizure, leaving just one possible culprit.

Investigators told the parents to cut communication with Mariel. Four months later, she would be charged and eventually convicted.

Yet mysteries remained. The baby had no external injuries, necessary in abuse involving blunt force. He had no broken bones, no fractures old or new, no bruises.

He suffered no injury to his spine or neck, and the entire right side of his brain was more or less spared—virtually impossible in abuse involving shaking. Investigators found no blood, vomit, or DNA indicative of an assault in Mariel’s home.

In fact, the babysitter cooperated with police in every way, passing two polygraphs that her attorney Marc Kurzman insisted she take as a condition of representation, and submitting to two psychological exams, which uncovered nothing more than a devout and docile soul. The pre-sentence investigator who evaluated Mariel’s likelihood to reoffend gave her the lowest score possible for somebody convicted of causing great bodily harm to a child.

The only motive the prosecutor could offer was an imaginative one, based on the admission that while Mariel may be a good person—perhaps a very good person—it was not impossible for good people to snap under stress and do a singularly terrible thing.

Mariel Grimm was a stay-at-home mom and homeschool teacher to her four children. During the trial, she was not allowed to have unsupervised contact with them.

Mariel Grimm was a stay-at-home mom and homeschool teacher to her four children. During the trial, she was not allowed to have unsupervised contact with them.

Dakota County Judge David Knutson, in an unforeseen show of mercy, ignored Pipenhagen’s very reasonable request for a five-year prison sentence.

He sentenced Mariel to just 90 days in jail. The babysitter and her 100 supporters celebrated with the soft singing of a hymn just beyond the courtroom doors.


Five months in hell

At 13 months, Will was a courageous crawler just beginning to walk. He was affectionate, full of babble, eager to absorb all the sights and sounds of the world. He loved Thomas the Tank Engine, swinging in the park, and watching airplanes throttle through the sky.

Will used to wrap his arms around his mother’s neck and tumble, laughing, into her lap. Jessica and husband John spent the first year of Will’s life stoking the budding intellect behind his eyes, watching with wonder his every summit. He was their firstborn.

But on September 22, 2016, the sudden seizure triggered an intense battle to save Will’s life.

Jessica rode in the ambulance to Regions Hospital. John raced to meet them. After surgery, the parents were presented with an unimaginable choice. Their son was comatose. Half of his brain was dying. A second operation could save his life, but there was a chance that if he ever woke up, he would never regain his mental or motor abilities.

They decided to save him.

“It is impossible to convey the tragedy and depth of our devastation and sorrow, as we watched our son fight for his life for days,” Jessica would later tell the court. “They thought he was going to die. You don’t get that from a bump on the head.”

For months the young parents stood vigil at the hospital, wondering if Will would ever breathe, eat, or drink on his own. After he was finally discharged, screaming pain and seizures would return him to the emergency room time and again.

Unable to trust another caretaker, Jessica quit her teaching job to raise the boy, adopting a new life of feeding tubes, medications, gut-wrenching physical therapy, and doctor’s visits, hoping that one day he could take just a few steps with a walker.

Neither parent could believe at first that Mariel was capable of harming their son. They asked every doctor who attended Will, seeking second and third opinions, yet no one could give them a different answer.

“We’re talking about an injury so extreme that it had the potential to immediately kill,” Jessica says. “We’re talking about a crumpled car on the side of a freeway. We’re talking about falling out of a second-story window head first onto concrete. We’re talking about Mariel violently assaulting our helpless baby and leaving him twitching, unconscious, dying.”

Will’s physicians agreed that, due to the enormous brain swelling and blood in the head, it certainly looked as if he had suffered some kind of trauma.

They consulted Dr. Mark Hudson, a child abuse specialist from the Midwest Children’s Resource Center who investigates everything from suspicious bruises to cracked skulls. He formed an opinion before the end of the day.

The baby was delivered to the hospital with bleeding between the brain and its outermost membrane, which is most commonly associated with trauma, Hudson wrote. He also noted the swelling of the left brain was so bad that its contents had begun to shift across the midline, compressing the right brain.

Because the minor traumas the parents described were unlikely to cause an injury so great, and because the babysitter noticed nothing amiss that morning, somebody was likely concealing foul play, Hudson reasoned. What that entailed, he couldn’t say.

At first, he believed an injury could have occurred up to eight hours prior to Will’s seizure. But he would later narrow that window of suspicion down to one. 


The last person on earth

Before September 22, 2016, Mariel Grimm was the last person anyone would suspect of hurting a child.

Born in the Dominican Republic, she arrived in America on a scholarship to attend a Catholic high school, where she met her eventual husband, Andy. She devoted her life to the wellbeing of children, first as a preschool teacher at Divinity Lutheran Church, then as a daycare provider. She returned frequently to the DR on missionary trips to see her parents, serve the church they built, and nurse orphaned infants with her own breastmilk.

She’d done the same for Will because his mother returned to work not long after he was born, and everyone knew he hated the bottle.

To Mariel’s extensive family of Minnesota in-laws, she was a child whisperer. They recall seismic family gatherings where hordes of children would run amok. They would count on Mariel to be their unfailing buttress of calm.

It was unlike her to ever raise her voice to children in tantrum, says Bethany Grimm, her sister-in-law. Some indescribable quality in Mariel’s voice tamed them easily.

The sentencing was a good day for the family. Mariel’s supporters included neighbors, church friends, old schoolmates, an alternate juror who could not be convinced of her guilt, and the mothers of other children she once looked after, who pledged they would continue to hire her if the state would allow it. When Judge Knutson departed so far from sentencing guidelines to show mercy, it felt like a miracle.

The next day, reality took hold once more. There were orders from Child Protection: Mariel could not be alone with her own children. Friends and family created a rotating schedule to keep them company while Andy worked.

For the next 60 days, Mariel was locked away in the Ramsey County Workhouse. She’d call crying for her children. 

The Grimms never anticipated a jury would find Mariel guilty. After all, the state couldn’t settle on a theory of how Mariel had harmed the boy. Was he shaken, beaten, or thrown? Nor could it explain how he suffered any of those possibilities without incurring a single mark.

“To make this conviction stick against Mariel is to take the most innate piece of who you are as a person and make someone believe the opposite of you,” said Bethany. “That’s how unbelievably ridiculous this is.”


Bad timing

At the core of the accusations, one element singled Mariel out: the timeline given by the child abuse specialist.

Hudson believed that because Mariel told investigators that the baby seemed normal to her that morning at daycare, that he had crawled and played, the event that caused his brain damage had to have happened after he was last known to be well. An injury so severe as to be life-threatening must have occurred immediately before the baby lost consciousness, he reasoned.

An unexpected rebuttal would come from an expert witness hired by the state.

Pediatric neuroradiologist Richard Patterson, whose specialty is held by just a handful of doctors in Minnesota, interpreted the CT scans for the court.

He described with scholastic patience the absence of a skull fracture, as well as the notable lack of scalp swelling. That was significant, he said, because swelling appears instantly and without fail following any sort of impact to the head.

The color of the blood, brighter than the surrounding tissue, was the first sign that something was wrong.

Then there was the swelling, which looked on the CT like a flat gray wash across the left hemisphere of the brain. That pairing of symptoms is an omen of death in two out of three cases where it appears, Patterson said.

The X-rays relinquish another clue: There was a slight variety in the opacity of the blood, which fades from bright white to dark cola over time. It meant that some of the blood could have been from an older bleed, or that new blood had not yet clotted. Patterson could not pinpoint exactly when the cause of the boy’s injuries occurred.

He suspected it would have been within “a couple of days of the first CT scan, but I can’t be more precise than that.”

Still, he believed the condition looked suspiciously like abuse. The likely cause: shaking.

Shaken Baby Syndrome is based on the theory that if a young child’s head is caused to whip violently, the brain will swell and be surrounded by bleeding, which will also appear behind the eyes.

But the thesis has powerful detractors in Minnesota. Dr. John Plunkett, a retired pathologist from Hastings, recalls a time when he subscribed without question to this thesis.

His point of departure came in 2001, when he started to wonder whether low-velocity impacts—short falls—could cause the same constellation of injuries. He studied fatal playground accidents and found that Shaken Baby Syndrome’s symptoms were not at all unique.

There were other studies that measured the amount of force that could be produced by shaking, which were mostly undertaken by biomechanical engineers baffled by the logistical workings behind the theory. Researchers attached sensors to infant-sized dummies and rattled them as hard as they could. They conscripted football players to do the same.

They found that the strongest of men could not shake an infant with enough force to reach any known injury threshold—not without some additional blunt force such as a fall, even a minor one.

Suddenly, Shaken Baby Syndrome began to slip out of use. By the late 2000s, the terminology became the more noncommittal “abusive head trauma,” a diagnosis without a mechanism.

Over the course of Mariel’s trial, all the state experts, when asked, said it was impossible to determine how much force is required to produce severe brain injury in an infant through shaking alone, since no one could experiment on actual infants.

Plunkett calls it ridiculous that in a world of models and simulations, doctors would claim ignorance of those studies.

Janice Ophoven, a forensic pathologist from Woodbury, blisters at the practice of allowing child-abuse doctors to render opinions about how and when a brain injury occurred, when it isn’t their area of training.

Bleeding between the brain and its membranes is often caused by the most trivial of household falls, she says. The moment a child falls ill isn’t always precisely when the bleeding begins. Days can elapse between a bump on the head and a seizure.

“The worst-case scenario is when you say, ‘OK, well, if no one has an explanation, I’m just going to call it abuse.’ It’s like a default diagnosis, and that’s just wrong.”

But assume for a minute that Shaken Baby Syndrome is biomechanically proven, Ophoven volunteers. The state, in Mariel’s case, should have had to explain how someone grabbed the baby either around the chest or around the arms, shaking him with enough force to cause a devastating brain injury, without leaving a single bruise.

The prosecution should have also had to explain how the babysitter managed to shake just one side of Will’s brain. Or why child-abuse specialist Hudson could not find the bleeding in the back of the eyes, a hallmark of Shaken Baby Syndrome.

Hudson once published a medical journal article stating that this symptom is found in about 80 percent of shaking cases. But during Mariel’s trial, he equivocated, claiming it was more like 40 percent.

“Jurors may not understand science, but they can count,” Plunkett says. “If the prosecution has seven witnesses and the defense has one or two witnesses, you can kiss it goodbye. Almost always. Somebody with money doesn’t get charged in these kinds of cases.”


Holes in the prosecution’s case

Of the two expert witnesses the Grimms could afford, one had never testified in a trial involving abusive head trauma. Minneapolis pediatric neurologist Donald Chadwick said he might have initially suspected abuse as well, but contended the state failed to prove it a medical certainty.

The other was Dr. Aristoteles Pena-Miches, a pediatric neurologist from Louisiana who came to the case in an unconventional way.

Pena-Miches attended medical school in Santo Domingo with Mariel’s father, who begged the neurologist to review Will’s charts. Pena-Miches was hesitant. In his nearly 30 years of testifying in abuse cases, he had never spoken on the side of the accused. Out of courtesy to a friend, he agreed to take a look.

“When I received the records, I couldn’t believe what I was seeing,” Pena-Miches says. “It was a total misrepresentation of the facts.”

The bleeding in Will’s head could have been a sign of traumas great and small, and could have been caused by many things other than abuse. It could be the result of an underlying blood disorder or a metabolic condition. Yet Hudson did not order tests to eliminate those possibilities.

Moreover, the overall volume of blood was small. The real menace was the swelling of the brain, which Hudson could not explain in court. It was unusual, he confessed, that the swelling was almost entirely one-sided.

It all had to do with “trauma and the subsequent effects of trauma,” he surmised. The exact cause and effect he dismissed as unexplored territories of medicine.

Pena-Miches began to search for an explanation, starting with the CT scans.

The first, taken moments before Will entered surgery, showed a brain that had lost all the landmarks of its anatomy. Swelling comes in two forms, vasogenic and cytotoxic, Pena-Miches would later testify. The former was more commonly associated with trauma. The latter is predominant when the brain is deprived of oxygen.

What the CT showed, Pena-Miches believed, was a textbook variety of oxygen loss. He theorized the baby could have had a form of posttraumatic stroke.

The timeline could not be as Hudson presumed, he deduced, because unilateral cytotoxic edema takes time to develop, and does not occur within minutes.

It’s the reason why neurologists caution parents to keep a close eye on babies following head injuries. Unlike older children and adults, they can’t communicate the slow encroachment of headaches, dizziness, amnesia, and lethargy.

Pena-Miches cited notes left by the radiologist who took the original CT scan, which read “ischemic injury”—stroke. 

He also pointed to an MRA taken four months later, which showed the baby had a small artery in his head that was arranged differently than it would be in most people. Pena-Miches proposed this could be a clue that the boy’s injuries were vascular in nature. If a blood vessel was blocked, it could deprive the brain of oxygen.

Pena-Miches offered another possibility. Some research shows that the nerves that act as the primary sensors of head trauma, through their stimulation of blood vessels, automatically react to accidental injury in unpredictable ways. As in the science of migraines, they could constrict an artery and deprive the brain of oxygen, then expand that artery and cause too much flow to go to one side of the head, triggering brain swelling.

“We as physicians, we have to be extremely careful not to use the power we have in the eyes of the law to commit what is called medical abuse,” Pena-Miches warned. “And medical abuse to me is when a physician does not think twice, analyze carefully the case, take all the possibilities, the pros and the cons, before arriving to a conclusion that may destroy somebody’s life.”

In her cross-examination, prosecutor Pipenhagen did not ask Pena-Miches a single question about his theories. Instead, she asked him about his friendship with Mariel’s family.

Later, when Pena-Miches had returned to Louisiana, Pipenhagen recalled the state’s medical experts, who said they weren’t particularly impressed with the stroke theory. They disagreed that the difference in Will’s artery was enough to cause the death of his left brain. But the nerve theory, they acceded, was solid scholarship.

The radiologist Patterson acknowledged that cases from the sports world gave credence to second-impact syndrome, meaning there is a period following minor head trauma where the brain is at greater risk of serious injury if a second trauma occurs.

“Is it possible that, you know, this was an accident?” he offered. “It is possible, it is possible. I mean, there’s lots of things that are possible.”


The felon on Copper Lane

After 60 days in the workhouse, Mariel Grimm is changed.

Before she went away, her world was small, filled with inconsequential hurdles like getting her kombucha in the morning and filling the inflatable pool before the height of summer.

As a felon, she will never teach again. She won’t see her grandfather in the Dominican Republic, who recently suffered two strokes, before he dies. She’s barred from leaving the country.

Sometimes she mistrusts the politeness of strangers, wondering if they’d treat her with the same kindness if they could see her brand. Ever since a jury condemned her, she fears judgment everywhere she goes.

Mariel wears an electronic monitor on her ankle, which prevents her from going so far as to take out the trash. One day shortly after her release, a neighbor came over with Christmas cookies. Mariel took a big bite before tasting the almond extract. She called her probation officer in panic, begging to take a breathalyzer because she’s forbidden to ingest alcohol. He told her to calm down.

The day Will was hospitalized, Mariel texted his mother Jessica for a prognosis. She never got a reply. When the doorbell rang that night, she ran to answer, thinking the parents had returned with news. It turned out to be the Eagan Police, who came with a warrant.

She was dying to call in the following days. Andy and his mother advised patience to avoid troubling the parents further.

Meanwhile, Jessica set up a blog tracking Will’s status, which Mariel read with apprehension. Finally, Jessica wrote that they would soon receive visitors. Mariel told a mutual friend that she intended to be the first.

The friend was visibly reluctant, Mariel recalls. He told her it would be better if she just stayed in contact through the blog.

Weeks passed. She read updates about how the parents were going to start bottle feeding, and she’d cry because she knew Will disliked bottles. She’d go running, then sit on the sidewalk and weep, wondering if his parents would let her watch him again.

Mariel called Jessica’s pastor. She wanted to go to the hospital, she told him, but wondered if it would add to their stress. Jessica had begun to sprinkle clues through her blog, implying she believed Will had been left in an unsafe situation. The pastor asked her to refrain.

Finally, Jessica wrote that Will had suffered a traumatic brain injury while at daycare, confirming that Mariel was suspected of abuse.

A year later, it’s clear that, in some ways, Mariel’s anguish will never end. But the Grimms’ life has become one of gratitude for every modest mercy.

Their Child Protection case will be over when their youngest turns three in March. Surprise visits have determined their kids are happy and cared for. Neighbors still bring cookies, and her church provides endless opportunity to fulfill her community service.

Mariel still reads Jessica’s blog, waiting and praying for Will’s gains while the many questions surrounding his injury continue to haunt her.

Various medical experts the Grimms consulted would tell them that unfortunately, sometimes the only sure way to diagnose what really happened is through an autopsy, and if the child lives, the truth may elude them forever.

“If that’s the case, we don’t want to know for sure,” Mariel says. “We’ll leave it as is. Whatever happens, it’s gonna be OK.”