16-year-old stabbed San Jose teacher to death in 1978, carried knife that read 'Teacher dear:' DA
Cold case of San Jose teacher killed outside her classroom solved 47 years later.
A confession heard by a relative, but never reported to police, helped Santa Clara County cold case detectives solve the murder of a San Jose teacher from 1978.
SAN JOSE, Calif. - Nearly 50 years after a young teacher was found stabbed to death in a San Jose high school hallway, South Bay authorities on Monday officially identified her killer as a 16-year-old who took his own life and had confessed to a relative and had been seen carrying a knife that had the words: "Teacher dear."
Cold case solved
The backstory:
The Santa Clara County District Attorney's Office said the boy's DNA led prosecutors in the cold case unit to Harry "Nicky" Nickerson, whom they say stabbed Diane Peterson on June 16, 1978, at Branham High School in San Jose, the day after school closed for summer break.
L: Composite sketch of a man with long hair next to an image of suspect Harry Nickerson. Left: Composite sketch of the murder suspect made from witness accounts. Right: Image of Harry Nickerson (date unknown). Photo: Santa Clara County DA
"She was killed with a single stab wound and a student at the time was walking by and actually saw Ms. Peterson and heard her cry for help," said Rob Baker, a deputy district attorney who oversees the cold case unit in the DA's office.
It wasn't until sometime this year that investigators learned that Nicky had told a relative he had killed the teacher – an allegation that had surfaced years ago, but couldn't be corroborated until now, prosecutors said.
Nicky died by suicide in 1993.
A motive for the killing was not released by the DA or San Jose police.
Branham High School teacher Diane Peterson killed in 1978. Photo: Peterson family via Santa Clara County DA
End of tragic mystery
"This marks the end of a terrible and tragic mystery," District Attorney Jeff Rosen said in a news release. "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."
On the day in question, a student found Peterson lying on the floor near her classroom with a single stab wound to her chest.
Nicky was an initial suspect, prosecutors said. In fact, he was booked four days after the teacher's death.
But the arrest didn't stick.
Then, in 1983, the family of a Branham student alerted police that their son claimed to have seen the killing and identified Nickerson as the one responsible.
The student, however, later denied making that statement.
In 1984, a witness told police that Nicky implicated himself in the killing, which he said was in response to her discovering him in the act of a drug deal, prosecutors said. In fact, authorities said, over the years, Nicky was arrested and convicted of various charges, including armed robbery, assault with a deadly weapon, and kidnapping.
DNA work
Between 2023 and 2024, the DA’s Crime Lab conducted extensive DNA work on the case, but it never yielded any positive results, prosecutors said.
This year, however, one of Nicky's relatives told investigators that the boy came to their home minutes after the killing and confessed to having stabbed Peterson.
Investigators would not reveal the exact relationship between Nickerson and the relative who heard the confession. Investigators said Nickerson was never publicly named a suspect and much of the information provided by witnesses would only be known by the killer and by police investigators.
The Campbell Union High School District released a statement which said:
"Though the events of this case took place decades ago, and prior to our current leadership, we recognize the seriousness of the incident and the impact it may have had on those connected to the school at the time. We hope this resolution brings peace and closure to the victim’s family and all those affected," the district said.
One of Peterson's relatives, who asked to remain anonymous, thanked investigators in a statement for "not giving up for 47 years…Diane was a beautiful and wonderful person who is missed dearly."
Featured
Decades-old San Francisco cold case prompts $100k reward in renewed effort
Authorities are bringing renewed attention to a homicide in San Francisco more than 30 years ago that has since gone cold, offering a $100,000 reward for information that leads to the arrest and conviction of a suspect.