The Most Dangerous Active Serial Killer In 2021

According to the Radford University/FGCU Serial Killer Database, 1987 was a particularly perilous year to live in the United States. Based on the database, a continuously updated index derived from data in a 2005 FBI symposium, that's the year the "number of separate serial killers operating in a given year in the U.S." was at its highest, with 189 working killers who'd slain two or more people. If the '80s were all about excess, it makes sense that we reached peak serial killer near the end of that decade.

Since then, despite some minor, annual deviations, that number has continued to decline. There's a lot of speculation around why, though as The Guardian reports, improved DNA and forensics capabilities is commonly cited for the drop in numbers. And that's not just trace DNA found at crime scenes, either; with the massive popularity of at-home genetic testing, sometimes all it takes is a distant relative curious about their genealogy to air your family's genetic dirty laundry, as we saw with the arrest of the Golden State Killer. As Thomas Hargrove, founder of the Murder Accountability Project, told Discover Magazine, "Serial murder has become a more dangerous pursuit." Maybe that's why in 2015, the last year Radford made stats available, they concluded only 30 serial killers were at work in the U.S.

Which serial killers are still out there?

Given the long, downward trend in the numbers of working serial killers, it's likely that 2021's number is far fewer than 30, though no one knows for certain. The tricky thing about serial killers, of course, is that authorities have to be aware that killings are happening in the first place, before they can pin a series of murders on any single, hypothetical killer. And with so many serial killers targeting vulnerable populations, like transients, runaways, or sex workers, it can be almost impossible to know whether an at-risk person is even missing, much less murdered.

But there are some instances where one discovery suddenly brings a series of deaths into chilling focus. That was the case in December of 2010, when, according to the New York Times, a police officer and his dog on a training exercise on a Long Island beach discovered skeletal remains just off a major parkway. It was the first discovery of the work of the Long Island Serial Killer (LISK), a case that would go on to span decades.

Who is the Long Island Serial Killer?

Following that initial discovery, three more sets of remains were found in the next few days, all of them later determined by police to have been sex workers, per the Times. According to Long, all had died by strangulation and were left in burlap sacks. Just months later — in March and April of 2011 — four more bodies were found. Of those, only one, 20-year old Jessica Taylor of Manhattan, has been identified. Several others, including a young Asian man (whom police believe was a sex worker) and a toddler who appeared to show no visible signs of trauma, according to, deviate from the pattern. It's not known whether the toddler was a victim of the LISK.

After the discovery of several more sets of partial or complete remains, police announced in November of 2011 that they believed that the deaths of the 10 victims could be attributed to a single killer. Police continued to investigate, with the FBI joining in 2015. Since then, five more sets of remains have been found on Long Island, and while some suspect these may be additional LISK victims, this remains only speculation at this point. Though LISK remains at large, he is believed to be responsible for anywhere from 10-16 deaths, says the LISK Podcast.

Here's what's happened recently in the case

In January of 2020, says the LISK Podcast, the Suffolk County Police announced at a press conference that they had found a belt buckle at one of the crime scenes and believed it to be the killer's. The unique, embossed buckle shows a pair of letters that read either "HM" or "WH," depending on its orientation. Later that year, Suffolk P.D. announced that, for the first time in New York state, a cold case homicide victim had been identified through genetic genealogy. The woman who'd previously only been known as the LISK's "Jane Doe #6" now had a name: Valerie Mack.

Each of these developments was exciting progress in such a lengthy investigation, but investigators seem to be no closer to determining LISK's identity. The police do have one suspect, however, a Long Island resident and former carpenter named John Bitrolff (pictured above). In 2014, DNA evidence linked him to the murders of two sex workers, in 1993 and 1994, and he was tried and convicted for those crimes (which are not counted among the victims of LISK). Bitrolff is currently serving consecutive 25-year sentences for those murders.

In 2017, reports Oxygen, Assistant District Attorney Robert Biancavilla publicly speculated that "there are remains of the victims at Gilgo that may be attributed to the handiwork of Mr. Bittrolff and that investigation is continuing," though no additional charges have yet been filed. As of today, 2021's most dangerous working serial killer remains unknown.