DNA testing leads to new murder charge in nearly 50-year-old cold case of slain Honolulu teen

Nearly five decades after her partially clothed body was discovered on the second floor of her Honolulu high school, modern DNA testing has led to an arrest that could solve the cold case murder of 16-year-old Dawn Momohara.

Momohara, discovered with an orange cloth wound tightly around her neck, was found on the second floor of the English building at McKinley High School in Honolulu on March 21, 1977. She was a sophomore at the school at the time.

Her former classmate, Gideon Castro, now 66, was living in a Utah nursing home when he was arrested Tuesday in the alleged homicide, according to the Honolulu Police Department. Decades after the case went cold, Castro has been charged with second-degree murder.

Deena Thoemmes, a lieutenant with the department’s homicide detail, credited the arrest to technological advances that enabled the use of DNA samples in a way that wasn’t feasible in 1977.

Thoemmes said officers found Momohara “lying on her back, partially clothed. It appeared that she had been sexually assaulted and she was pronounced dead at the scene.”

Later examinations revealed injuries and other evidence confirming that she was sexually assaulted and strangled.

Momohara had received a call from an unknown man the morning before her slaying, according to Thoemmes, citing homicide detectives. Later that day, she informed her mother that she would be visiting a shopping center with some friends. It was the last time her mother heard from her.

After her body was found, detectives interviewed multiple friends, family members and acquaintances about the case — including Castro — but had failed to identify a suspect despite following up on numerous leads.

Composite sketches of a person of interest as well as a possible suspect vehicle has been available on HPD’s website for years, as it asked the public to send in any tips about the case.

In 2019, however, police began processing several items recovered from the murder scene for DNA evidence, including a pair of blue shorts and underwear. The following year, they managed to obtain the DNA profile of an unidentified male from the sperm that was on Momohara’s shorts.

With assistance from the FBI and Homeland Security Investigations, detectives located Castro and managed to match the unidentified DNA profile to him earlier this month, authorities said. Castro is now in custody in Salt Lake County and awaiting extradition to Honolulu, according to Thoemmes.

“I want to thank all the individuals and agencies that made today’s arrest possible,” she said, noting that HPD also worked with police in the greater Salt Lake City area. “Thank you all for your dedication and commitment to the tireless pursuit of justice for Dawn and the Momohara family.”