Hawaii investigators have arrested a 66-year-old man at a Utah nursing home in connection with a five-decade-old cold case murder.
DNA testing linked U.S. Army veteran Gideon Castro to the long-unsolved murder of 16-year-old college student Dawn Momohara on March 21, 1977.
Momohara’s body was found by a teacher on the second floor of a building at McKinley High School in Honolulu. Medical examiners said she was sexually assaulted before being strangled.
An orange cloth was wrapped tightly around her neck and the murder caused fear throughout the island, while the girl’s killer remained at large.
Although the case remained unsolved, DNA evidence from the crime scene, including shorts and underwear worn by Momohara, was preserved by law enforcement, which was analyzed in March 2019.
A year later, in March 2020, forensic investigators found a partial DNA profile taken from semen at the murder scene, leading police to the Castro family.
Gideon Castro and his brother William were initially identified as suspects a week after the murder, and although they said they knew Momohara, neither was arrested.
Both brothers came under suspicion again in 2019 because they shared partial DNA matches. After DNA from William’s child ruled him out as a suspect, detectives had to track down Gideon.
Dawn Momohara, 16, was found sexually assaulted and fatally strangled at her high school on March 21, 1977, with her murder remaining unsolved for decades.

Momohara’s body was found at McKinley High School in Honolulu, Hawaii (pictured), and authorities kept DNA evidence from the crime scene for decades that was retested in 2019.
When Gideon was interviewed nearly 48 years ago, he told investigators he met Momohara at a school dance in 1976, and admitted they occasionally spoke on the phone.
This detail may have identified him as a person of interest in the case, as it was known that the morning before Momohara was murdered, she had told her mother that she was receiving a call from an unknown person.
She told her mother that she and a few friends went to Ala Moana Center with some friends, and as Honolulu Police Lt. Deena Thoemmes said at a news conference this week, “That was the last time Dawn’s mother saw or heard her.” daughter.’
After Momohara’s body was found at the school, detectives tracked down a witness who claimed he had seen a man loitering in his car near the same building in which she was later found the night before the murder.
The car was described as a sedan believed to be a Pontiac LeMans, Buick Century or Buick Regal, with louvered rear windows, a maroon bottom and a white vinyl top, the car reported. Star advisor.
“The car was parked on the grass and a man was observed walking out from the ground floor stairs,” Thoemmes said this week. “The witness was driving around in his car, but the man and the car had already left.”

A witness claimed that the night before the murder they saw a man loitering in a sedan outside the school building where Momohara was found the next morning (photo is a 1977 police sketch of the suspect vehicle)

A composite sketch of a suspect (pictured), described as an Asian male between 18 and 22 years old with shoulder-length hair, was created at the time, but police said it “did not provide any substantial leads at the time.”
The man was described as Asian and between 18 and 22 years old, with shoulder-length hair and about 150 pounds. Gideon Castro is said to have been 18 years old at the time of the murder.
A composite sketch was made, but Thoemmes said the sketch “did not provide any substantial leads at the time.”
“Despite following up on numerous leads and interviewing multiple individuals, investigators were unable to identify a suspect at that time,” she added.
For decades it was an unsolved cold case, until the case was submitted for further DNA testing in March 2019 and a partial DNA match was found a year later.
Detectives tracked down the Castro brothers as DNA matches more than three years later, and authorities first went to William in Chicago, Illinois in November 2023 to obtain a sample from him or one of his children.
When his child’s DNA ruled out William as a suspect, detectives turned to his brother Gideon, and the FBI and Homeland Security assisted in the investigation because they discovered he was living in a nursing home in Utah.
After obtaining DNA from his son in another state using ‘secret’ methods, it was found to match the sample found at the Momohara murder scene, with further testing of Gideon confirming the match, Thoemmes said .
Utah police arrested Gideon at the nursing home and charged him with manslaughter.
He is now awaiting extradition to Honolulu, where he will stand trial for Momohara’s murder.