A Denver man convicted of murdering a 4-month-old girl had his conviction overturned Tuesday and was released after being imprisoned for 27 years.

Stephen Martinez, 58, was convicted of first-degree murder in 2000. He had been arrested in October 1998, shortly after the death of Heather Mares, the child of his then-girlfriend. Martinez confessed to shaking Mares during questioning, which his attorneys argued was a false confession.

At his original trial, prosecutors posited that, while Martinez was watching the child, he shook her violently and slammed her head against a wall, fracturing her skull. Martinez was sentenced to life in prison without parole.

The overturning comes after Martinez’s counsel filed a motion last week asking for post-conviction relief. In a filing, his attorneys argued that new evidence not available in 2000 showed Mares died of a heart attack following a bout of severe respiratory illness, and that Martinez had ineffective counsel due to his original lawyers not attempting to introduce evidence of Mares’ medical history.

The filing said Mares had several health issues during her short life and was sick with pneumonia leading up to her death, but that no other explanations for Mares’ death beyond child abuse and shaken baby syndrome was given at trial.

“Shaken baby syndrome” is a term used to describe injuries consistent with children being shaken. The diagnosis has come under increased scrutiny in recent years as a number of convictions based on the diagnosis have been overturned.

In a response filing dated the same day, the Denver District Attorney’s Office said an extensive review of the case showed Martinez did not have effective counsel and concurred with the defense’s request to vacate the conviction.

In a courtroom packed with reporters, Martinez’s family, defense attorneys and a prosecutor asked District Judge Andrew Luxen to vacate the conviction.

Jeanne Segil, an attorney with the Korey Wise Innocence Project who represented Martinez, called Mares’ death a tragedy, but asserted she died from pneumonia.

“Not every tragedy is a crime,” Segil said. “Stephen Martinez did not cause her death.”

Mares’ family opposed the overturning of Martinez’s conviction and his release.

Andre Mares, a cousin of the child’s father, spoke on behalf of the family during the hearing. In his statement, Mares said the child’s death has destroyed their family, with many members requiring mental health treatment through the years because of the loss.

He said the family missed out on her life’s milestones due to Martinez’s actions. Mares said releasing Martinez would show there was an “expiration date” on justice.

“This was not an accident,” Mares said and asked the judge to honor the jury’s original sentence.

Luxen said he would grant the motion to vacate Martinez’s sentence because the court believed the new evidence would have likely changed the outcome of the original trial.

The judge then asked if any other of the child’s family members would like to speak — to which her mother stood up.

Kimberly Estrada said through tears that her daughter was an innocent, defenseless baby. She called Martinez a “monster” and said releasing him would put other children in danger.

“My life was stopped 27 years ago, along with my family’s,” she said. “Please your honor, please. I beg you. Don’t let him out.”

Martinez did not look at them and stared ahead as the family members spoke. 

While speaking directly to Estrada, Luxen apologized for the loss of her child and said the pain her family has felt is incomprehensible.

He said the decision to vacate Martinez’s sentence was not easy. He said he was sorry as he told Estrada he would be granting the motion and ordering Martinez’s release. Estrada sobbed as Luxen spoke to her.

The charges against Martinez were dismissed without prejudice.

Following the overturning of the conviction, Andre Mares told The Denver Gazette his family is worried about Martinez being released and questioned why the court was seemingly ignoring the medical evidence shown at Martinez’s original trial.

“To try to get us to swallow that pneumonia caused these fractures, these subarachnoid hematomas, everything like that, it doesn’t make sense,” Mares said. “It’s just crazy that the court system would accept that.”

Denver District Attorney John Walsh said after the hearing that the DA’s office conducted an independent investigation, which included consulting with medical experts who verified the defense’s claims that pneumonia was a likely cause of death.

He said since this evidence was not introduced in the 2000 trial, the DA’s office joined the defense in asking for the vacated conviction on the grounds of ineffective counsel.

“We concluded that we could not meet our burden of proving the case beyond a reasonable doubt if we were to take it to trial today. So, for that reason, we moved to dismiss the case in its entirety,” Walsh said.

Theresa Garcia, Martinez’s aunt, said her family is excited to welcome her nephew home after nearly three decades.

“We were heartbroken when he was wrongfully convicted,” Garcia said. “We, his family, are beyond thrilled to welcome Stevie home.”