CHEYENNE — A 57-year-old woman charged with first-degree murder in the death of a newborn boy in early 1988 repeatedly told investigators she was never pregnant around that time, despite DNA testing showing it’s 1.97 million times more likely she’s the baby’s mother than anyone else.
Cheyenne resident Eva Martinez was arrested Tuesday on suspicion of first-degree murder in the death of who has become known over the past 38 years as “Baby John Doe,” whose body was gruesomely discovered Feb. 28, 1988, near a culvert off a county road, according to court documents.
She made her first appearance in Laramie County Circuit Court on Wednesday morning, where was advised that first-degree murder carries penalties of life in prison or death.
Wearing solid dark-brown scrubs top and wide white-and-orange striped pants, she simply answered “yes” when Circuit Court Judge Antoinette Williams asked if she understood the charge against her, and again when asked if she wanted a public defender.
While the grisly discovery of the boy’s body happened more than 38 years ago, it wasn’t until 2021 that advanced DNA testing allowed investigators to advance the case and identify Martinez as the boy’s probable mother, according to an affidavit of probable cause written by Detective Sgt. Ryan Martinez of the LCSO (no relation).
When first interviewed by detectives on Dec. 22, 2025, Martinez “repeatedly denied knowing anything about Baby John Doe or having any children or pregnancies around that time frame,” the affidavit says.
It was during that interview that a sample of her DNA was taken, and when she was interviewed again months later after results showed the strong probability of her being Baby John Doe’s mother, she maintained her first story, according to the affidavit.
“She denied having any knowledge of Baby John Doe, having knowledge of anyone else who was responsible for Baby John Doe’s death, or why Baby John Doe’s body was placed in the culvert at Happy Jack Road and McKinney Drive,” the affidavit continues.
She claimed she wasn’t in Cheyenne around that timeframe, but investigators could not verify that information.
Martinez graduated from Cheyenne Central High School in 1987, and at some point afterward moved to Las Vegas, where she worked for about the next 20 years before returning to Cheyenne, the affidavit says.
The Discovery
Martinez would have been 18 on Feb. 28, 1988, when Laramie County Sheriff’s Office deputies responded to a call at Happy Jack Road and McKinney Drive just southwest of the boundary for F.E. Warren Air Force Base.
What they found was anything but routine, the affidavit says.
People who had been walking in the area discovered the dead baby near a culvert.
“Their juvenile son had initially noticed a dog chewing on something in the area, and they later realized it was a deceased baby,” the affidavit says. “It was determined that the deceased baby had initially been inside the culvert prior to the dog moving it.”
The baby was “abandoned, unclothed, deceased … discovered near the roadway,” according to an LCSO report announcing Martinez’s arrest.
“An autopsy concluded that the baby was a fully developed, full-term, 6.5-pound baby,” according to the report. “The autopsy found no evidence of significant injury, congenital anomaly, or disease.”
It also was determined that the baby was born alive and remained alive for “an amount of time due to air being in the baby’s lungs and stomach,” the report says.
However, at the time the cause and manner of the boy’s death were undetermined.
“The LCSO subsequently investigated a number of leads about the deceased baby,” the affidavit says. “All attempts to try and identify who the deceased baby boy was, the deceased boy’s parents, and why the baby was left along the road were unsuccessful.”
What The Father Said
In 2021, the LCSO partnered with Othram Inc., a Texas laboratory that specializes in forensic genetic genealogy.
Othram was able to identify two matches for possible close relatives to Baby John Doe, which led investigators to a son of Match 1, who tested 331 trillion times more likely to be the baby’s father than anyone else.
In interviews with the LCSO, that man admitted to having a relationship with Martinez around the time Baby John Doe was born and abandoned, but said Martinez told him at the time that the baby had been stillborn and that a doctor in Fort Collins “dissolved” the baby, the affidavit says.
That contradicts Martinez’s repeated statements that she was never pregnant at that time.
“He and Eva were in a serious relationship for several years and lived together for part of it,” according to the affidavit. “During their relationship, Eva had become pregnant. He was excited to have a baby and believed she was as well.”
That was until one day, he told investigators, when she went into labor and her water broke.
Eva and her older sister left and were gone for at least 24 hours, and when they came back told him about the stillbirth.
“He was suspicious of the story because there was never any funeral held for the baby he knew of,” the affidavit says.
At the time, he was young, didn’t pay attention to news and wasn’t aware of Baby John Doe.
He also thought Martinez had likely arranged to give the baby up for adoption for money. Their relationship ended soon after.
What Martinez Said
After talking to the father, investigators contacted the Larimer County Coroner’s Office in Fort Collins.
The coroner said he couldn’t find any record of Eva Martinez having given birth to a baby in that county or a record of a baby having died in a local medical facility, the affidavit says.
Along with claiming she was likely in Las Vegas at the time Baby John Doe was born and died, Martinez claimed the biological father could’ve had the baby with any number of women.
“Eva claimed that biological father had numerous girlfriends during that timeframe who could be the baby’s mother,” the affidavit says. “When asked what DNA testing would indicate, Eva said that it wouldn’t show anything as far as her relationship to Baby John Doe.”
Despite those results coming back showing a strong probability she was the baby’s mother, Martinez maintained she wasn’t.
“Eva claimed that the individual referred to as biological father is not credible,” the affidavit says. “Eva denied having any knowledge of biological father playing a role in Baby John Doe’s death or being left in the culvert.”
In the meantime, she remains in the Laramie County Detention Center on a $100,000 cash-only bond set by Judge Williams on Wednesday.
“The state does have some concern she may be a flight risk given the charges,” the prosecutor argued via closed-circuit video conferencing.
The judge set the bond, then scheduled a June 18 preliminary hearing for Martinez, where it will be determined if there’s enough evidence to support a first-degree murder charge.
Laramie County Sheriff Brian Kozak said the charge against Martinez is satisfying for his office and investigators who have worked for decades to get justice for Baby John Doe.
“I’m just so proud of Sgt. Martinez and everyone involved,” he told Cowboy State Daily on Wednesday. “We didn’t forget about an unknown baby, and I’m so happy for this.”
He also said the Wyoming State Crime Laboratory conducted the final DNA testing and was crucial to the investigation.
Greg Johnson can be reached at greg@cowboystatedaily.com.
