Cheyenne parents charged with murder in death of 4-month-old
CHEYENNE — Months after a 4-month-old infant died of suspected homicide, police have arrested the child’s parents on charges of first-degree murder.
The two Cheyenne residents, 24-year-old Joseph Hanson and 23-year-old Juliette Martinez, initially brought their child to Cheyenne Regional Medical Center in August to be treated after the infant allegedly suffered a seizure.
The child was airlifted to Denver for advanced treatment, but he did not recover and was removed from life support on Sept. 8.
The child had injuries that appeared to be from physical abuse. Autopsy results determined that the cause of death was homicide, according to court documents.
Both suspects in the death of their child, Hanson and Martinez, were arrested Wednesday.
Though their booking sheets said both Hanson and Martinez were charged with first-degree murder and aggravated child abuse, only the murder charges were referenced during their initial appearances Thursday afternoon in Laramie County Circuit Court.
Judge TJ Forewood set each parent’s bond at $500,000 cash only, based on the severity of the alleged offense.
The suspects are presumed innocent until proven guilty in a court of law. This case remains under investigation by the Cheyenne Police Department.
At the hospital
Hanson and Martinez took their son to CRMC on Aug. 8, 2025. The child had experienced a seizure, according to court documents. Though he was found having a seizure at approximately 11:30 a.m., he wasn’t brought to the hospital until 12:17 p.m.
Hanson and Martinez left at approximately 3 p.m., informing staff that Hanson would return soon. At approximately 5:48 p.m., Hanson had yet to return, and staff were unable to reach him by phone.
At approximately 5:45 p.m., a Cheyenne Police officer was dispatched to the hospital. Staff informed police of the situation, including that Hanson had told staff that Martinez had “twin resentment” for the baby boy, who has a twin sibling and an 18-month-old sister.
Staff determined the baby needed advanced medical treatment but were unable to contact the parents to get consent to airlift the baby to Children’s Hospital Colorado.
As a result, the responding officer went to their residence to connect them with hospital personnel, according to the release.
Medical evaluations in Denver revealed extensive injuries, according to court documents.
According to the child’s medical records, he had suffered brain and skeletal injuries, including fractures in his legs and wrist, a spinal fracture and a possible fractured rib.
A few days following the initial incident, police spoke with the Children’s Hospital Colorado care team via Zoom, who advised that the injuries were consistent with child abuse.
One doctor referenced a portion of the child’s medical records, which read, “Diagnosis is abusive head injury and child physical abuse. If (the child) expires, this will be fatal child physical abuse.”
Another doctor added that the child’s imaging and clinical picture are consistent with a nonsurvivable diffuse hypoxic injury and severe cerebral edema.
Doctors also confirmed the injuries were caused within days of the child being admitted to medical care.
On Sept. 2, 2025, the child tested consistent with brain death. He was removed from life support and pronounced deceased Sept. 8, 2025, a month after he was brought to medical personnel.
Interviews
Officer Timothy Campolong initially contacted Martinez at her home, where she lives with Hanson and their children. Martinez noted that she observed her son having fast breathing before taking him to the hospital. She called for Hanson, and both agreed the child’s “breathing was off,” according to court documents.
They picked him up and noticed he was shaking, but they were unsure if it was a seizure at first. The child would not take a bottle or stop shaking, according to Martinez’s statement to police.
Campolong spoke with Hanson, explaining that the medical staff were concerned and wanted the officer to ensure that the infant wasn’t being neglected or abused.
Hanson reportedly told Campolong that he was unsure what had happened, that he had come home for lunch and “the symptoms just kinda unfolded fast and then, you know, it just went from like zero to a hundred real quick.”
Hanson stated he asked Martinez three times if anyone had hurt the baby; she said no. When asked if it was something police should be concerned about, Hanson reportedly said no again, according to court documents.
During a search of the residence, detectives noticed several holes in the wall about the size of an adult fist, as well as a table frame in the basement and broken glass pieces on the table top in the garage.
Detective Webster, who wrote the affidavit of probable cause, also spoke with Hanson’s mother over the phone. She told Webster that she watches the kids while Hanson is at work, and that when she left for Arizona on Aug. 4, 2025, the baby was fine.
In separate interviews with Hanson and Martinez, conducted on Aug.11, 2025, the parents made various claims about the events leading up to the seizure, according to court documents.
Hanson stated he was awake all night, and the baby was in the living room with him. The child woke up in the early morning, at which point Hanson fed him a bottle, and he went back to sleep. Hanson fed the baby another bottle the following morning and left the house between 7:30 a.m. and 7:40 a.m.
He confirmed the baby was in Martinez’s care while he was at work. He also admitted to punching the holes in the walls, stating it had occurred before the twins were brought home.
During her interview, Martinez stated she was up and with Hanson in the living room. She said she went to bed around 5 a.m. and did not wake up until 11:20 a.m. After she woke up, she stated she noticed Hanson was home, got up to grab her breast pump, and then went back to the bedroom, at which point she noticed the infant’s breathing.
She took a video of the baby and sent it to Hanson’s mother, who told them to take the infant to the hospital, according to court documents.
Phone evidence
Both parents’ phones were seized for evidence, according to court documents. Investigators found that Martinez’s phone was active on Snapchat, Tik-Tok and iOS text messages between 8:03 a.m. and 09:28 a.m., inconsistent with the times Martinez stated she was asleep.
Her phone was also found to have 58 missing text messages between 6:42 a.m. and 11:45 a.m, according to court documents.
The investigation also uncovered several internet searches completed after the child was having seizures, including:
. Shaken baby syndrome symptoms
. Shaken baby syndrome symptoms go away
. Signs father gave baby shaken baby syndrome
. Seizures in a 5-month-old baby
. Seizures in a 5-month-old baby longer than 5 minutes
. Diabetes in a 5-month-old baby
. Can high blood sugar cause seizures in diabetics
. Seizure high blood sugar baby
Hanson’s phone showed he left the residence at 7:18 a.m. and returned at 10:50 a.m., according to court documents.
The investigation
On Sept. 4, 2025, a few days before the child was removed from life support, police again tried to question the parents. Both invoked the right to counsel, according to court documents.
Months after the infant’s death, on March 20, detectives received the completed autopsy report from the Adams and Broomfield County Coroner’s Office, which determined the cause and manner of death to be homicide.
Detectives then submitted probable cause affidavits to the District Attorney’s Office for the arrest of Hanson and Martinez. On Wednesday, both were arrested without incident.
This story was published on April 10, 2026.