At 11:38 a.m. on October 17, 1998, Stephen Martinez called 911 in Denver, Colorado, to report that his girlfriend’s infant daughter was choking and aspirating blood. He said 4-month-old H.M. had been sick with an “upper respiratory” illness and was turning purple and going limp.
The 911 operator instructed Martinez, who was 30 years old, on how to administer cardio-pulmonary resuscitation. Paramedics arrived. They noted that H.M. had blood-tinged fluid in her throat and nose. They intubated the girl and then took her to Denver Health Medical Center.
While treating H.M., doctors at the hospital reported a fracture in the back of H.M.’s skull, a subdural hematoma, and pulmonary disease. H.M. was pronounced dead at 6:12 p.m.
Kimberly B., H.M.’s mother, and Martinez had only been dating for a few months, and he had moved in with her in September. On the morning of October 17, Kimberly left their home at 11:30 to run a few errands.
Martinez gave a written statement to the police. He said he was watching TV when he heard H.M. crying in her bedroom. He gave her a bottle, returned to the TV, then heard the child gasping and choking.
“I grabbed her little mouth, and she spit up some formula (I think it was formula) and then gasped and started kicking then I put my finger in her mouth and throat to see if there was something stuck in there, she then started spitting up blood and gasping harder,” Martinez wrote. “I then tried to wipe her up and picked her up and she spit up on me and I then got on the phone and called 911.”
He repeated that account in a call with a victim’s advocate.
At the hospital, Kimberly told the doctors that H.M. had been fussy the night before and choked while feeding that morning. She told a nurse that she had fallen while holding her daughter a few weeks earlier. Later, she told police that it was actually Martinez who had fallen while holding H.M.
Police arrested Martinez that night. Martinez signed a Miranda waiver, and Detective Matthew Murray began interviewing Martinez at 1:30 a.m. The interview was videotaped.
Martinez told Murray that he had tripped over a telephone cord and fallen while holding H.M. two-and-a-half weeks earlier. He said he thought he had protected H.M.’s head but wondered if she had hit something during the incident.
During the interview, Martinez said, “Actually I’d like to stop right there.” Murray continued the interview and told Martinez that his account didn’t add up. He said that H.M.’s fatal injuries occurred on October 17, when Martinez was alone with the child.
“I saw the CAT scans,” Murray said. “That injury, the child could not have lived two weeks, period.”
Later, Murray said: “And you were a little frustrated, and maybe you put the baby down too hard, maybe you even picked the baby up like this a little bit and [the] baby accidentally hit its head. You put the baby down, and then you’re trying to help the baby because you weren’t intending to go in there and hurt the baby. That was not on your mind.”
“I would never hurt a baby intentionally,” Martinez said.
“But maybe accidentally, Stephen,” Murray said, adding that Martinez might be able to get anger management or probation if he admitted to shaking H.M.
During the interview, Murray used a doll to demonstrate how he believed Martinez shook H.M. Eventually, Martinez picked up the doll, shook the doll, and made a gesture approximating the slamming of the doll into another object.
“[H.M., H.M.]! please stop crying,” Martinez said as he shook the doll, adding that he “dinged” her head on the crib. “When I dinged her on the back of the head, I felt terrible,” Martinez said. “I’m not a bad person. I’m not a murderer, you know what I mean. I’m not a bad person.”
Martinez was charged with first-degree murder.
His trial in Denver County District Court began on January 3, 2000, with Judge Shelley Gilman presiding. Jurors watched the videotape of Martinez’s interview, including his use of the doll.
Dr. Amy Martin, a forensic pathologist and the assistant coroner for the Denver Office of the Medical Examiner, had performed the autopsy on H.M. Martin listed the cause of death as a homicide caused by complications from blunt trauma to the head.
She testified that H.M.’s fatal injuries were due to Shaken Baby Syndrome (SBS), which is sometimes referred to as abusive head trauma.
She said that H.M. displayed the so-called “triad” of symptoms—retinal hemorrhaging, subdural hematoma, and brain swelling—that were then said to be indicative of child abuse through violent shaking. “When you have a violent shaking, a violent whiplash situation, the brain actually sort of bangs around on the inside of the skull,” Martin said. “There’s tiny blood vessels that are connected to the brain and the dura, and those blood vessels can tear in the situation, and that is actually the cause of the subdural blood, from the tearing of those tiny little vessels.”
Martin testified that H.M.’s skull fracture would not usually come from a simple fall and that the signs of trauma she observed appeared to have occurred within a day of the child’s death. She said that swelling of the brain can cause respiratory issues.
Martin had examined H.M.’s lungs and said in the autopsy that H.M. had early acute pneumonia. She testified that “early” meant within a few hours of death.
As part of her testimony, Martin used a doll to demonstrate whiplash shaking to the jury.
Dr. Patti Rosquist, a pediatrician who specialized in treating child abuse, testified that an infant would quickly develop symptoms of distress after receiving a subdural hematoma. Over the objection of Martinez’s attorney, she testified how these injuries might occur.
“There have been multiple studies of series of witnessed falls or witnessed accidents where babies have had similar kinds of injuries,” Rosquist testified. “And in those studies, babies who had similar kinds of injuries, the subdural hematoma, have been things like a fall from a multiple story building. Being in a high-speed motor vehicle accident either as a pedestrian hit by a high-speed motor vehicle or, for example, an unrestrained passenger in a high-speed motor vehicle accident, so those are the kinds of witnessed injuries that can lead to a similar sort of injury.”
Rosquist testified that it was her understanding that H.M. had been “eating normally, behaving normally, and then all of a sudden had a change in behavior,” and she said that this was consistent with shaking a baby.
Rosquist also testified that the observed bruise patterns on H.M., which she described as having a “narrow angle,” were inconsistent with the child hitting the crib, as Martinez had said in his videotaped statement.
Martinez did not testify, and his attorney did not call any other witnesses.
During the state’s closing argument, the prosecutor returned to Rosquist’s testimony regarding the force required to cause subdural hematomas.
“We now know the necessary force that takes us to that level of violence. The violence that must be exerted to exert that kind of force on the back of the child's head,” the prosecutor said. “And now we know his level of violence; we know his true actions. What did he have to have done? What did he have to do? And if he was doing that, he had to have known what he was doing, and he had to have known what it was going to do to her.”
The jury convicted Martinez of first-degree murder on January 7, 2000, and Gilman sentenced him to life in prison without the possibility of parole.
Martinez appealed. He argued that Judge Gilman erred in allowing Rosquist to testify about the extreme accidents that might cause subdural hematomas. He said that this allowed the state to assert that Martinez must have shaken H.M. with intent to harm and with more force than he demonstrated with the doll in the video.
On December 20, 2001, the Colorado Court of Appeals reversed Martinez’s conviction and ordered a new trial. It said that Rosquist’s testimony had likely misled the jury, because it centered on the most extreme causes of subdural hematomas and implied intent on Martinez’s part. “Put another way, to determine how much force defendant must have inflicted on the baby, it is the minimum force, however characterized, necessary to inflict a subdural hematoma in a child that is relevant,” the court said.
The state appealed, and the Colorado Supreme Court reinstated the conviction on June 30, 2003. It said this part of Rosquist’s testimony was properly admitted, not to show Martinez’s intent, but to help the jury understand other parts of her testimony.
On December 6, 2004, Martinez filed a pro se motion for a new trial. He said his attorney had provided ineffective assistance, and the state had violated his constitutional rights when Murray continued questioning him after he had asked for the interview to stop. A judge in Denver District Court denied the motion without a hearing on May 12, 2005.
By the time Martinez learned of the denial, the deadline to appeal had passed. On June 12, 2006, Martinez asked for an extension, saying he had not received timely notice of the denial. After a judicial assistant said it would have been in their “habit and routine” to send the order to Martinez, a judge ruled that the order of denial was “probably” mailed to Martinez and dismissed his motion. The appellate courts rejected his appeals on this issue.
Martinez turned to the federal courts, filing a pro se petition for a writ of habeas corpus in U.S. District Court for the District of Colorado. The petition raised many of the same claims Martinez made in his 2004 motion.
On July 14, 2009, a federal magistrate judge recommended that Martinez’s petition be denied. The judge did write that Martinez had obtained prison records showing he received no mail during the period when the judicial assistant said the order was sent to him. But she rejected his claim of ineffective assistance, which Martinez said was based on his attorney not challenging the state’s experts on the cause of H.M.’s death. Martinez’s admission during his interview that he shook H.M. and struck her head against the crib undermined this claim, the judge said. A federal judge adopted the recommendation on August 10, 2010.
In 2022, attorneys with the Korey Wise Innocence Project at the University of Colorado Law School and the Stinson law firm began representing Martinez. In 2024, the attorneys submitted a formal memo to the Conviction Review Unit (CRU) of the Denver County District Attorney’s Office, asking for a review of Martinez’s case. Both sides retained experts to review the evidence.
On April 17, 2026, Martinez’s attorneys filed a motion for a new trial. The filing, which said Martinez was innocent, reflected the mounting scientific evidence since the trial that physicians and others had frequently misdiagnosed SBS and abusive head trauma, reporting abuse where it never existed.
H.M. was born with lung problems. She was diagnosed with an upper respiratory infection when she was 10 weeks old. A month before H.M.’s death, Kimberly took her to an urgent-care facility after the infant vomited blood-tinged digested milk. The motion said this was a symptom of persistent lung disease, and the hospital reported this visit as a case of “possible viral infection.”
The motion included reports by three medical experts who had reviewed H.M.’s medical records for Martinez’s legal team. The reports said H.M. died of a chronic respiratory infection that began at least a day before she died.
Dr. Roland Auer, a neuropathologist at the University of Saskatchewan College of Medicine, wrote that H.M. “died due to lung infection and this infection existed before the day of the incident. Her lungs were incompatible with life. And the hypoxia in the lungs caused her heart to stop. These were the causes of death, not blunt impact trauma.” H.M.’s deteriorating lung functions impacted her blood circulation, forcing blood normally destined to her brain into her retinal vessels, causing the hemorrhaging “commonly misattributed” to SBS. Martin’s autopsy had noted faint purplish bruising with three superimposed lines on the back of H.M.’s head, which Martin attributed to trauma. Auer said that was wrong; plastic tubing at the hospital created the marks. “The lines are due to medical intervention, not inflicted trauma,” he said.
Dr. Matthew Goldsmith, the medical director of the Pediatric Intensive Care Unit at St. Louis Children’s Hospital in Missouri, agreed that H.M. died from respiratory failure. Goldsmith said that although H.M. did have a skull fracture, it was impossible to say that the injury was the result of abuse; it could have happened from the accidental fall as described by Martinez. Goldsmith said that the autopsy incorrectly listed blunt trauma as the cause of death. Head injuries don’t cause the kind of “clinical deterioration” that was present in H.M.’s case, he said. “Indeed, in almost 25 years of practicing pediatric critical care medicine, I have never seen head trauma cause the death of a child in the manner in which [H.M.] died.”
Dr. Peter Dehnel, a pediatric hospitalist for CentraCare Health in St. Cloud, Minnesota, said that the hematomas and brain bleeding found on H.M.’s CT scan would not have caused her death and were likely related to the child’s fall weeks earlier. H.M.’s history of chronic illnesses put her at risk for hematomas, he said. “It is more likely than not that Mr. Martinez did not do anything that would have caused substantial injury to, or the death of [H.M.],” Dehnel said.
Dr. Kenneth Monson, an associate professor of mechanical engineering at the University of Utah and director of the university’s Head Injury and Vessel Biomechanics Laboratory, said in a report that recent research had shown that short falls can lead to severe brain injury and skull fractures and could have caused H.M.’s head injuries. He said that violent shaking of infants is often associated with structural neck injuries, particularly of the ligaments, but that those injuries were not reported in H.M.’s case.
Monson’s report also said that Rosquist had given misleading testimony when she compared the injuries from shaking to those from a high-speed accident or a fall out of a building. He said her testimony ignored all the variables that could make such an incident more or less harmful to a child. “It is critical to understand that a simple fall, such as the one described, has the potential to generate forces that are comparable to those an occupant might experience in a serious car accident,” he wrote.
The motion also included a report from Richard Leo, a law professor at the University of San Francisco and an expert on false confessions. He said that Martinez’s confession, which he said was more accurately described as an “interrogation-induced statement,” had no indicators of reliability or trustworthiness. “In my professional opinion, Mr. Martinez speculatively accepted responsibility for causing the death of [H.M.] not based on any personal knowledge that his actions did cause [H.M.]’s death, but in response to coercive psychological pressure to comply with Detective Murray’s interrogation demands and inducements,” Leo said. In his report, Leo wrote that Murray assumed Martinez’s guilt and used a wide range of interrogation techniques—including lying, threatening harsh treatment, sympathizing, and making promises of leniency—to get a confession.
The motion also included a 2026 affidavit from Martin, the coroner. Now retired, Martin said that when she performed the autopsy, she was not aware that H.M. had a history of respiratory problems or that Martinez had reported an earlier fall with H.M. “The possibility of several intervening conditions which could have contributed to her demise introduces a degree of uncertainty as to the manner of [H.M.]’s death,” Martin wrote. “Hence, a jury today would reasonably doubt the manner of [H.M.]’s death.”
Martin recanted much of her trial testimony about the impact of violent shaking on an infant. She said that many of the statements she made had “been disproved due to changes in medical science. Significantly, I no longer believe that shaking or acceleration/deceleration was a significant factor in the death in this case.”
At the trial, Martin had used a doll to demonstrate how an adult might shake a child. She said in her affidavit that the demonstration was inappropriate and that the prosecutor’s description of her demonstration was misleading, because the description suggested that the demonstration indicated Martinez had intended to harm H.M.
The CRU retained its own experts to review the evidence. These reports were also included in the motion for a new trial.
Dr. Robert Bux, a board-certified pathologist and the former coroner for El Paso County, Texas, said in his report, “This case involved a medical rush to judgment.”
He said H.M.’s medical history, which included the earlier fall and imaging that showed lung problems, were either ignored or not available to the hospital staff. He said that he did not believe that the small fracture in H.M.’s skull played a part in her death, because the autopsy didn’t reveal any traumatic brain injuries. He said H.M. died from bronchopneumonia, not trauma, and that her manner of death was natural.
Dr. Csaba Galambos, a pathologist and pediatric pulmonologist at the University of Colorado School of Medicine, said that H.M.’s pneumonia started 1½ to 2 days before her death. While being placed on a ventilator can cause pneumonia, H.M.’s level of inflammation indicated that the pneumonia began before she arrived at the hospital. “The patient’s pneumonia was so extensive and severe that it could by itself have caused the patient’s death,” Galambos wrote. “However, this does not exclude other potential contributors, including a potentially fatal trauma to the head.”
In its response, also filed on April 17, the state agreed that Martinez’s conviction should be vacated, based on his trial attorney’s ineffective representation. “Specifically, the People agree that trial counsel was ineffective in failing to retain medical experts for the purpose of exploring alternative explanations for the cause of the child’s death,” the response said. “The People agree there is a reasonable probability that, but for that failure, the outcome of the trial would have been different.”
On April 21, 2026, Judge Andrew Luxen vacated Martinez’s conviction, dismissed the case, and ordered his release from prison. At the hearing, H.M.’s family, including Kimberly, had urged him not to let Martinez go free.
Jeanne Segil, the supervising attorney at the Korey Wise Innocence Project, told the Denver Post that the medical evidence showed that H.M. died of pneumonia, not abuse.
“That night after making the same statements four times explaining that the baby had choked, telling them—four different times— the truth, eventually [Martinez] made a false confession and said that he had shaken the baby," Segil said. "We now know today that that was false.”
– Ken Otterbourg
Posting Date: 05-11-2026
