Honolulu Police Arrest Suspect in Dawn Momohara’s 1977 Murder

The last time Dawn Momohara’s mother heard from her daughter, she told her she was going to meet friends at a mall in Honolulu.

Hours later, after 16-year-old Dawn failed to return home on a Sunday afternoon in 1977, she was reported missing, The Honolulu Star-Advertiser later reported.

The next day, March 21, 1977, shortly before students began Monday morning at McKinley High School, Dawn was found dead on the second floor of what was then known as the English Building. She was half dressed and had an orange cloth wrapped tightly around her neck.

Police determined at the time that she had been strangled and possibly sexually assaulted, but the suspect was unknown for decades.

On Tuesday, nearly 500 years after Dawn’s body was found, Gideon Castro, 66, was arrested and charged with her murder, Honolulu Police Department Lt. Deena Thoemmes at a press conference. He graduated from McKinley High School. Castro in 1976 and knew the Dawn.

Mr. Castro was identified after a six-year investigation in which modern DNA testing technology helped match crime scene evidence to his DNA, police said.

In the days after the murder, Mr. Castro and his brother William were questioned by the police along with several other classmates. Mr. Castro later told police that he met Dawn at a school dance in 1976. He said his last contact with her was at a school carnival in February 1977, when he told her he was in the US Army Reserve.

Her brother William told the police that he met Dawn through his brother. There were no suspects involved.

The only initial police lead in the investigation was a description of a man and a car that witnesses saw in the high school parking lot the night of Dawn’s disappearance. In the week after her death, Honolulu police stopped and searched all vehicles similar to what the witness described as a maroon and white Pontiac sedan, according to a 1977 article in The Star-Advertiser.

Police also canvassed the neighborhood, carrying photos of Dawn and asking residents if they had seen her when she went shopping on Sunday, another post said. It is unclear if he made it to the Ala Moana Center, where he told his mother he was going to meet a friend.

The case went cold for decades until 2019, when detectives in Hawaii reinvestigated Dawn’s murder with the help of DNA testing technology. Using DNA evidence found on the shorts in 1977 and more advanced technology, police were able to identify Mr. Castro and his brother William Castro, would be a match.

Beginning in 2023, Lieutenant Thoemmes said, investigators traveled to Illinois and Utah to secretly take DNA samples from the Castros’ older children to determine which of the brothers’ DNA was found in the crime scene. After tests failed to identify William as a suspect, investigators obtained Gideon’s DNA.

Gideon Castro’s DNA was a match, police said. He was arrested at a nursing home in Utah on Tuesday and charged with second-degree murder. It is unclear whether he had legal representation.

Lieutenant Thoemmes said both federal and local law enforcement were involved in the “tireless pursuit of justice for Dawn and the Momohara family.”

Kirsten Noyes participated in the research.