LOS ANGELES — Stephen Kay was a fresh-faced prosecutor just 27 years old and three years out of law school when circumstances handed him the Charles Manson “family” murder case.

Over the next half-century, it would come to define his career and lead to death threats that to this day he worries a Manson sycophant might try to carry out.

“I don’t dwell on it, but I’m careful. I always look around to see if I’m being followed or anything,” the retired prosecutor said recently as he paused to discuss the case that punctured the peace, love and happiness movement that flowered in the late 1960s.

Kay helped lock up Manson family members but never really relinquished the case in his decades in the Los Angeles County district attorney’s office. He attended some 60 parole hearings over the years where he argued the killers should never be released.

“The crime was simply too heinous,” he said.

It was 50 years ago this week that Manson, a small-time career criminal who had reinvented himself as a hippie guru, dispatched a band of disaffected young followers on a deadly weekend rampage that would terrorize Los Angeles and forever imprint on the American consciousness the image of the slight, steely-eyed cult leader as the face of evil.

On that first night, Aug. 8, 1969, Manson sent a handful of his young, mostly female followers to the palatial hilltop estate of actress Sharon Tate with orders to kill everyone there.