When Massapequa Park resident Rex Heuermann was arrested in July of 2023 on suspicion of being the “Long Island Serial Killer,” the media rushed to learn as much as it could about the man who was eventually charged with killing a string of sex workers that occurred over more than a decade. However, without the tenacity of the victims’ family and friends — underscored in Liz Garbus’ 2020 scripted film Lost Girls and now in her documentary series Gone Girls: The Long Island Serial Killer — it’s possible that the Suffolk County police may never have learned about the existence of many of the people who went missing.

While there are some victims whose names and stories are still unknown, DNA testing and renewed media interest are helping to ensure that all...