Police recently arrested a 66-year-old man at a nursing home in Utah on suspicion that he murdered a girl who attended his high school in Hawaii nearly five decades earlier – with modern DNA technology implicating him.
Gideon Castro’s arrest came in connection with the killing of Dawn Momohara, 16, who was found dead the morning of 21 March 1977 at the campus of McKinley high school in Honolulu.
Momohara was a sophomore at the school, according to the Honolulu police department.
She had gone missing the night before she was found dead, having not returned home after telling her mother she was going to meet friends at a shopping center.
Momohara’s body was discovered the next morning. She was pronounced dead at the scene, and an autopsy determined that she died of asphyxia due to strangulation.
She had injuries to her neck, and a medical examiner also determined that she had sustained injuries consistent with sexual assault. The examiner classified Momohara’s death as a homicide.
At a news conference Tuesday, about 48 years after her body was discovered, Lt Deena Thoemmes of the Honolulu police department announced that – with help from authorities in Utah – Castro had been charged in Momohara’s murder and arrested.
Authorities said Castro graduated from McKinley high school in 1976 and knew Momohara.
In the days after the murder, Castro and his brother, William, were among the many classmates, friends, family members and acquaintances of Momohara to be interviewed by the police. At that time, neither sibling was considered a suspect.
Gideon Castro had told authorities that he had met Momohara at a school dance in 1976 and had last spoken with her at a school carnival in February 1977. He said they talked for 15 minutes, and he told her that he was in the US army reserve.
His brother, William Castro, told police at the time that he had met Momohara through his brother.
On the day Momohara disappeared, authorities said she received a call from an unknown male before telling her mother she was going to a shopping center with friends.
Two witnesses at the time also reported to authorities that they saw a man and a car near the school building the night before she was found dead.
Authorities released a sketch of the man and the car. But it “failed to provide any substantial leads” and authorities were unable to identify a suspect at that time.
In 2019, detectives in Hawaii began analyzing various items and samples collected from the murder scene using modern DNA testing technology. In 2020, using advanced DNA technology, the police obtained a partial genetic profile of an unidentified male from a sample taken from her shorts.
Police in 2023 then said they received information suggesting that William Castro or Gideon Castro could be potential suspects – but they did not elaborate.
With help from the FBI and Homeland Security Investigations, detectives located the Castro brothers and their biological children.
They traveled to collect DNA samples from the adult children – and, according to the police, a DNA profile obtained from William’s child cleared him.
Further tests and analysis revealed that Gideon Castro’s son was a biological child of the unidentified male whose DNA was found at the scene.
And so, earlier in January, detectives traveled to Utah and obtained a DNA sample from Gideon himself, which they say matched the DNA profile from the shorts.
Investigators obtained a warrant to arrest Castro. And on Tuesday morning, he was apprehended at a nursing home in Utah on a charge of second-degree murder.
Authorities later reported that Castro was awaiting extradition to Honolulu.
“I want to thank all the individuals and agencies that made today’s arrest possible,” Thoemmes said at Tuesday’s news conference. “Thank you all for your dedication and commitment to the tireless pursuit of justice for Dawn and the Momohara family.”