Chances are anyone under the age of 30 who watches "Confluence" won't recognize a pre-Internet tool for shedding light on several unresolved Northwest murders and disappearances three decades ago.

That tool is microfilm: tiny records, in this case, of old newspaper articles about those grim events, published long ago in Idaho newspaper The Lewiston Tribune.

"Confluence" directors Vernon Lott and Jennifer Anderson use the quaint-looking documents in their documentary as a visual cue that those occurrences took place in a distant time.

"It was a completely different world," says Lott. "A world in which the procedure for handling the sudden vanishing of a 12-year-old girl like Christina White was different. Police waited 24 hours before they did anything. Now we have Amber Alerts so we don't waste time."

White, of Asotin, Wash., disappeared April 28, 1979, while her mother waited for her at a rendezvous point. Two years later, 22-year-old Kristin David went missing in Lewiston, Idaho. In 1982, three other Lewiston adults — Kristina Nelson, 21; her stepsister, Brandi Miller, 18; and former Air Force Cpl. Steven Pearsall, 35 — simultaneously vanished. Evidence strongly connects all five events.

The bodies of David, Nelson and Miller turned up, but the whereabouts of White and Pearsall are unknown. Lott, a Lewiston native, was a child during those frightening years.

"It was something kids talked about on the playground," he says. "It has haunted anyone who grew up in Lewiston during that time, and it was a story I always wanted to tell."

Lott and his co-director and spouse, Anderson, reached out to family members and police investigators to speak on camera. Those "Confluence" interviews are noteworthy for delicate handling of a painful subject.

"We didn't press, we just wanted to let the family members tell their stories," says Lott. "They were comfortable with us because they knew we were from Lewiston."

Officials long vexed by this cold case opened up, too.

"They wanted to talk about it," Lott says. "Tom Greene, captain of the Lewiston Police Department (LPD), named, for the first time, a longtime person-of-interest."

That person left Idaho some years ago, threatening to sue police, who lack evidence against him, for harassment. Though Lott and Anderson were advised not to name him in "Confluence," they do so anyway.

"I felt that because the LPD had been forthcoming," says Lott, "we'd make that jump with them and deal with the consequences."

Tom Keogh: tomwkeogh@gmail.com.