After Man Spends 27 Years in Prison, Denver Court Overturns Conviction for 1998 Infant Death

Kim Estrada left her Denver home for fifteen minutes on October 17, 1998, to go to the bank. When she returned, her four-month-old daughter, Heather Mares, was being carried to an ambulance.

Heather died at the hospital later that day. The infant had suffered a complex skull fracture, brain bleeding and ruptured blood vessels in her eyes, according to court records. Her cause of death was complications of blunt force trauma to the head, the autopsy concluded.

Stephen Martinez, now 58, was arrested in connection to Heather’s death. He had been staying with Estrada and was looking after her baby while she ran errands. He called 911, reporting that the baby was choking, according to his arrest affidavit. During an interrogation, Martinez told police that he shook Heather because she was crying and struck her head on the edge of her crib. Martinez was convicted of first-degree murder and sentenced to life in prison without the possibility of parole in January 2000.

After nearly three decades behind bars, a Denver judge ordered Martinez’s release on Tuesday, April 21. New evidence brought by his attorneys indicates Heather may have died from pneumonia rather than the injuries to her head.

“Not every tragedy is a crime,” attorney Jeanne Segil said during Tuesday’s hearing. Segil is assistant director of the Korey Wise Innocence Project, which provides free legal services to Colorado prisoners who argue that they were falsely convicted. “Stephen Martinez is an innocent man and has spent over 27 years in prison for a crime he did not commit.”

In their petition for post-conviction relief, Martinez’s attorneys argue that he was coerced into falsely confessing to shaking Heather and striking her head. They attribute her skull fracture to an accident two weeks before her death, when Martinez allegedly tripped while holding the baby.

While the original autopsy determined that Heather died due to the blunt force trauma, recent reviews of the case found the baby’s lungs were also severely damaged due to pneumonia, according to the petition. An independent review by the Denver District Attorney’s Office “largely confirmed” the claims, says District Attorney John Walsh. With this information, the medical examiner who conducted the original autopsy has now “acknowledged a reasonable doubt” about the baby’s cause of death, he adds.

“Unable now to meet our ethical and legal burden of proof beyond a reasonable doubt, we were obliged to dismiss the case,” Walsh says. “I want to emphasize that there was no misconduct on the part of the prosecutors or detectives who worked on the case in the late 1990s. This is simply an example of the criminal justice system being willing and able to reassess a case when necessary.”

Martinez’s original attorneys failed to present any evidence of Heather’s pneumonia at his trial, the petition argues, so jurors were not given any other explanation for the baby’s death besides abuse. The DA’s Office agrees that Martinez’s counsel was “ineffective” and “there’s a reasonable possibility that the outcome of the trial would have been different” if the attorneys had investigated an alternative cause of death.

With both parties in agreement, Judge Andrew Luxen ruled to vacate the murder conviction and drop the charges against Martinez.

Heather’s family is devastated by the outcome. Estrada addressed the court in tears on Tuesday, begging for the judge to keep Martinez behind bars.

“My daughter was healthy and she was afraid of [Martinez]. Anytime she saw him, she would hold onto me like if someone was going to take her,” Estrada says. “My message to him is: I hate you. You’re a monster. You don’t deserve to be in this world with regular people, or your family, if I can’t be with mine.”

Case Details

Though media reports refer to Martinez as Estrada’s boyfriend, she claims he was more like a roommate, whom she had met through work. Heather died around seventeen days after he moved in, Estrada alleges. In police reports from the time, she described Martinez as jealous of her children and angry whenever Heather cried. In 2000, she told the Denver Post that her other child previously claimed Martinez had threatened him.

During Martinez’s murder trial in 2000, the question was never whether he fatally injured Heather, but whether he did it knowingly. Martinez’s attorneys argued that Martinez only shook Heather with minimal force and that her head accidentally hit the crib during the shaking, focusing the defense on the idea that he didn’t realize shaking could hurt her, according to court records. In addition to Heather’s injuries, when police responded to Martinez’s 911 call, they found blood on the baby’s crib sheets. Martinez admitted to putting the bloodied sheets in the washing machine before officers arrived, according to his arrest affidavit.

The sudden shift to blaming Heather’s death on pneumonia has left the family reeling.

“The injuries he inflicted were horrific,” Andre Mares, one of Heather’s relatives, said to the judge on Tuesday. “Medical experts testified that the force required was massive and violent…which kind of goes against common sense about a pleading of pneumonia. This was not an accident. This was not minimal force. It was deliberate, rage-filled conduct.”

“The jury rightly convicted him of first-degree murder,” Mares added. “To shorten that sentence now…would tell every family of every murdered child that the same clock runs against them.”

The petition filed by Martinez’s attorneys claims that Heather had been sick for weeks leading up to her death. It references time spent in neonatal intensive care after her birth for trouble breathing, a respiratory infection at two months old, as well as an urgent care visit at three months old. His attorneys also allege that Heather was sick the night before she died, the Denver Post reported.

Estrada disputes some of the petition’s findings, claiming that her baby was never in urgent care and was not sick the night before her death.

The vacated conviction comes as the science behind shaken baby syndrome has come under increased scrutiny in recent years. In the last decade, 25 people have been exonerated of murder, manslaughter or child abuse charges involving shaken baby syndrome, according to the National Registry of Exonerations.

“This is not an easy decision,” Judge Luxen told Heather’s family. “I feel for you and your family. I’m certain that everyone in this room feels for you and your family. I’m very sorry.”

Martinez did not address the court on Tuesday, but he provided a statement to the media via the Korey Wise Innocence Project.

“It’s hard to find the right words on a day like this,” Martinez said. “After more than 27 years in prison for a crime I did not commit, I am finally free. I am looking forward to reuniting with my family and rebuilding my life.”

Estrada has fought to keep Martinez in custody for decades. In 2001, the Colorado Court of Appeals overturned Martinez’s conviction, ruling that medical expert testimony provided during the trial was misleading. In 2003, the Colorado Supreme Court disagreed with the lower court and reinstated the first-degree murder conviction.

This latest court battle came at a heartbreaking time for Estrada. Her 26-year-old son, Brandon, died from renal failure less than two weeks ago. Estrada says she was pregnant with Brandon during the original murder trial.

“It’s a lot,” Estrada says. “I hate the judicial system and will never have faith in it again.”