'20/20' REPORTS ON NEW HAMPSHIRE MURDER MYSTERY THAT UNRAVELED ACROSS THE COUNTRY FOR OVER THREE DECADES, EVENTUALLY SOLVED WITH CRUCIAL CLUES PROVIDED BY CUTTING-EDGE DNA TECHNOLOGY AND A MYSTERIOUS 5-YEAR-OLD GIRL

'20/20' Features Exclusive Interview With Daughter of Man Responsible for Crimes '20/20' Airs Friday, March 20 (9:01 - 11:00 p.m. EDT), on ABC

"20/20" reports on a murder mystery that unraveled across the country for over three decades, including details about how cutting-edge DNA technology and a mysterious 5-year-old girl provided crucial clues that helped authorities solve the case. The story began in 1985 in the deep woods of New Hampshire's Bear Brook State Park when authorities discovered a barrel - and a second barrel years later - containing the unidentified bodies of a woman and three children. In 2018, a local podcast renewed interest in the cold case and sparked a movement of citizen sleuths, working alongside homicide detectives, plus a genetic genealogist who uncovered the true identities of three of the four victims just last year.

"20/20" features an exclusive interview with Diane Kloepfer who is the daughter of Terry Rasmussen, the serial killer authorities linked to the case, who by then was dead. Kloepfer recalls the moment she learned her father's shocking identity and his horrible crimes, and reflects on what life was like with him. The two-hour program also includes exclusive interviews with siblings of victim Marlyse Honeychurch; and Armand Beaudin, the father of presumed victim Denise Beaudin. ABC News cameras captured the emotional moments at a funeral last fall where the gravestones of two of the Bear Brook victims were finally given their names and as Rasmussen's daughter met family members of some of the victims who lost their lives at the hands of her father. "20/20" includes interviews with those vital to the case including genetic genealogist Dr. Barbara Rae-Venter; web sleuths Rebekah Heath and Ronda Randall; and Jason Moon, host of "Bear Brook," New Hampshire Public Radio's hit investigative podcast that helped crowdsource an investigation. The program raises questions that remain today about who is the unidentified fourth victim, and who and where is her mother. "20/20" airs Friday, March 20 (9:01 - 11:00 p.m. EDT), on ABC.

"20/20" is anchored by David Muir and Amy Robach. David Sloan is senior executive producer.