How Modern DNA Testing Helped Cops Solve 1977 Murder Of 16-Year-Old

A 66-year-old man has been arrested and charged with second-degree murder in connection with a nearly five-decade-old cold case, thanks to modern DNA testing. The Honolulu Police Department arrested Gideon Castro in connection with the 1977 murder of Dawn Momohara, who was 16 years old at the time.

She was found dead on the grounds of McKinley High School on March 21. Castro and his brother, William, were questioned, along with other classmates, but no one was identified as accused.

Castro was one of her former schoolmates who joined the US Army Reserve after graduation.

According to a 1977 article in The Star-Advertiser, the police made all efforts to identify the murderer. When police first started their investigation, they merely had a description of a man and a car that a witness noticed in the high school parking lot the night Ms Momohara went missing, as per NBC News.

In the weeks following her death, Honolulu police stopped and checked all vehicles that matched the witness' description of a maroon and white Pontiac car.

The case remained unsolved for decades until 2019, when detectives in Hawaii reopened the investigation into Ms Momohara's murder, using advanced DNA testing technology. By analysing DNA evidence found on her shorts in 1977, investigators were able to identify Gideon Castro and his brother, William Castro, as potential suspects.

In 2023, investigators conducted DNA tests on the adult children of both brothers. This testing excluded William Castro as a potential suspect. Further analysis confirmed that Gideon Castro's DNA matched the evidence collected at the crime scene. It was later determined that Ms Momohara had been sexually assaulted and strangled.

According to Deena Thoemmes, a lieutenant with the department's homicide detail, the arrest was made possible by technological advancements that made it possible to use DNA samples in a way that was not practical in 1977.

Gideon Castro is now in custody in Salt Lake County and awaiting extradition to Honolulu.