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

Hours later, after Dawn, 16, didn’t return home that Sunday afternoon in 1977, she was reported missing, The Honolulu Star-Advertiser later reported.

The next day, March 21, 1977, just before students began Monday morning classes at McKinley High School, Dawn was found dead on the second floor of what was then called the English building. She was partially clothed and an orange cloth was tightly wrapped around her neck.

The police determined at the time that she had been strangled and possibly sexually assaulted, but a suspect would not be identified for decades.

On Tuesday, nearly a half-century after Dawn’s body was found, Gideon Castro, 66, was arrested and charged with murdering her, said Honolulu Police Department Lt. Deena Thoemmes at a news conference. Mr. Castro graduated from McKinley High School in 1976 and knew Dawn.