(SAN JOSE, Calif.) — The brutal murder of a school teacher, stabbed in the chest at a California high school in 1978, has finally been solved, according to authorities, with the district attorney’s office now revealing the then-16-year-old killer confessed to a family member minutes after the murder.
Diane Peterson was found stabbed at Branham High School in San Jose one day after school ended for the summer. And though they had suspects over the years, her murder had never been solved.
One of those suspects, Harry “Nicky” Nickerson, has now been confirmed as the killer, the Santa Clara County District Attorney’s Office announced Monday.
Earlier this year, investigators learned Nickerson had confessed to a family member he committed the murder. Investigators met with the family member, who admitted to police that Nickerson came to their home minutes after the murder and confessed to stabbing Peterson, solving the decades-old murder, according to the district attorney’s office.
The district attorney’s office will not be filing charges against the family member who revealed Nickerson admitted to the murder, the DA’s office told ABC News.
“The relative did not participate in the killing and did not provide protection or assistance. Just a witness. The relative was emotional and appeared relieved after having kept a secret for almost 50 years,” the office said in a statement to ABC News.
“The relative did not expressly say why they did not come forward,” the office said, saying it is “reasonable to surmise it was out of fear of retaliation.”
In the years after the murder, Nickerson was arrested and convicted of armed robbery, assault with a deadly weapon and kidnapping, according to the DA’s office. He was shot and critically injured in 1984 while attempting a drug robbery, but no charges were filed against him “given the circumstances,” the district attorney’s office said.
Nickerson died by suicide in 1993, according to the district attorney’s office.
“This marks the end of a terrible and tragic mystery. Ms. Peterson would have been a senior citizen today if she had not crossed paths with this violent teenager. I wish she was. I am pleased that we have solved this case, even though the murderer is not alive to face justice. I wish he was,” Santa Clara County District Attorney Jeff Rosen said in a statement.
There is no statute of limitation on murder in California.
“Let this serve as a solemn reminder: no matter how much time passes, we will continue to seek the truth — because every victim matters, and every life deserves justice,” San Jose Police Chief Paul Joseph said in a statement.
A student found Peterson stabbed to death in the high school hallway in 1978, the district attorney’s office said. Peterson suffered a single stab wound to her chest, according to the district attorney’s office.
The murder occurred one day after school ended for the summer, while teachers were cleaning their classrooms, according to the district attorney’s office.
A witness had previously told police that Nickerson confessed to the crime and that he had seen Nickerson “carrying a knife that had written on it: ‘Teacher Dear,'” according to the district attorney’s office. Police were not able to corroborate that claim, according to the district attorney’s office.
Nickerson had long been a suspect in the killing, according to the district attorney’s office. Nickerson allegedly had a “strong similarity to a composite sketch based on eyewitness accounts of the attack,” according to the DA’s office.
The family of a student told police in 1983 that their son had claimed to have seen the killing and that he identified Nickerson as the killer. The student later denied this, according to the district attorney’s office.
In 1984, a witness told police that Nickerson implicated himself in the murder, claiming he killed Peterson after he was discovered making a drug deal, according to the district attorney’s office.
Extensive DNA work on the case in 2023 and 2024 was unable to identify the killer, according to the district attorney’s office.
A family member of the victim, who asked to not be identified by police, thanked investigators for “not giving up for 47 years.”
“Diane was a beautiful and wonderful person who is missed dearly,” the relative said in a statement.
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