A cold case homicide that haunted San Jose for nearly 50 years has finally been solved.
On June 2, 2025, the Santa Clara County District Attorney’s Office announced that 16-year-old Harry “Nicky” Nickerson was responsible for the brutal stabbing. The Branham High School teacher Diane Peterson was murdered in 1978.
Peterson, 25 at the time, was found dead with a stab wound to the chest near her classroom the day after the school year ended. The revelation closes one of California’s oldest unsolved murders. Although justice cannot be served in court, since Nickerson died in 1993 by suicide.
Cold Case Homicide Solved After 46 Years
Nickerson, who was not a student at Branham High School, reportedly confessed to the killing just minutes after it occurred—but only to a family member. That confession did not surface until 2024, when the relative contacted investigators, finally unraveling the mystery.
“This marks the end of a terrible and tragic mystery,” said District Attorney Jeff Rosen. “Ms. Peterson would have been a senior citizen today… I wish she was. I am pleased that we have solved this case, even though the murderer is not alive to face justice.”
