Horror in the Woods: 'People Magazine Investigates' Looks at the Keddie Cabin Murders Cold Case

PEOPLE's true crime series reviews a mystery and new leads in the 1981 cold case

Three members of a family murdered. A killer or killers never caught. A 35-year-old cold-case mystery heating up, while survivors hope for justice long-denied.

People Magazine Investigates, which airs its upcoming episode Monday, Nov. 28 on Investigation Discovery, delves deep into the unsolved killings of four people. The episode is entitled “Cabin 28: Horror in the Woods.”

The show examines the 1981 killings of single mom Sue Sharp, 36; her son Johnny, 15; her daughter Tina, 12; and Johnny’s friend Dana Wingate, 17. The murders were discovered by Sue’s daughter Sheila, then 14, who was spending the night next door at the faded former tourist resort in the northern California community of Keddie. The show traces Sheila’s decades-long desire to learn what happened to her family and who is responsible.

“This didn’t happen in a few seconds,” Mike Gamberg, a special investigator for the Plumas County, California, Sheriff’s Office, says of the attacks, in which the victims were bound and assaulted with knives and hammers. “Whoever was there, whoever did this, took their time,” he says.

“With that kind of chaos going on, there had to be more than one person to control the scene,” Gamberg says. “It was evil.”

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The episode explores the theories and leads of investigators at the time, none of which resulted in arrests or charges. But with a new sheriff who took office in 2010, the case is getting a fresh look — and authorities have discovered new and previously forgotten or overlooked evidence Gamberg says may at last confirm the killers’ identities.

People Magazine Investigates airs Mondays (10 p.m. ET) on Investigation Discovery.