US police have arrested a suspect in the unsolved murder of a Honolulu teenager whose death shocked the high school where her body was discovered nearly five decades ago. They said the man arrested, Gideon Castro, was one of her former schoolmates who joined the US Army Reserve after graduation.
Dawn Momohara was found dead on the morning of March 21, 1977, on the second floor of a building at McKinley High School in Hawaii's capital, according to the Honolulu Police Department. She was 16 years old and a sophomore there.
Officers at the time were confronted with a horrific scene. Momohara was partially clothed and lying on her back with an orange cloth tied around her neck, Honolulu Police Lt. Deena Thoemmes said at a news conference Tuesday. A later autopsy determined that Momohara had been strangled to death, and the medical examiner said there were signs of sexual assault.
Although police obtained an unknown man's DNA sample from the teenager's clothing, they were unable to identify a suspect. Authorities would not investigate significant leads into the murder until 2020, after a detective used new technological methods to investigate.
By September 2023, DNA testing had led investigators to two possible suspects: brothers Gideon Castro and William Castro, both of whom were interviewed shortly after Momohara's murder. At the time, Gideon Castro told police he met Momohara at a school dance in 1976, shortly before he graduated, police said. William Castro said in interviews that he and Momohara spoke periodically on the phone but denied having any relationship with her.
After forensic tests narrowed the pool of possible suspects to the Castro brothers, Thoemmes said, police traveled to Chicago, where William Castro lived, to secretly take a DNA sample from one of his children and use it as a comparison. The comparison ruled out William Castro as a suspect, and Gideon Castro, now 66, was arrested at his Utah nursing home on a charge of second-degree murder.
Gideon Castro will be extradited back to Honolulu, Thoemmes said.
“On behalf of the Honolulu Police Department, I want to thank all of the individuals and agencies that made today’s arrest possible,” the lieutenant said. “Thank you for all of your dedication and commitment in tirelessly pursuing justice for Dawn and the Momohara family.”