What Is Mitochondrial Analysis, Used On Accused Gilgo Killer's Pizza?

MASSAPEQUA PARK, NY — In elementary school, many of us were taught that mitochondria are the "powerhouse" of the cell. But in forensic science, mitochondria are powerful enough to solve serial murder cases.

Rex Heuermann, 59, who was charged on Friday with six counts of murder in the deaths of three sex workers, was linked to the women through mitochondrial analysis, Suffolk County District Attorney Ray Tierney said.

Female hairs were found on the remains of Amber Costello, Melissa Barthelemy, and Megan Waterman, but due to the amount of time their bodies were exposed to the elements, the evidence was degraded, and a typical DNA analysis could not be performed, prosecutors said. The female hairs did not belong to the deceased women.

At a news conference on Friday, Tierney said it wasn't until 2022 that forensics could use mitochondrial analysis to identify the DNA.

Dr. Deborah Silva, professor and director of the Forensic Science Program at Hofstra University, spoke with Patch about mitochondrial analysis and its importance in forensics.

What Is Mitochondrial Analysis?

Mitochondria are found in human cells, or one of a cell's"organelles." They are responsible for a cell's energy production, biochemical reactions, metabolic activity, and promote cell multiplication and cell growth.

Mitochondria are unique in that they have DNA that's different from nuclear DNA.

People inherit nuclear DNA from both parents, but mitochondria DNA comes solely from the mother, so all children from the same mother will share the same mitochondrial DNA (mtDNA).

"For example, I have a brother and a sister. We all have the same mtDNA. Same as my mom, her brother, my grandmother," Silva told Patch in an email.

This DNA is not unique to each person, but is actually a matrilineal marker.

Why Use It In Forensic Investigations?

Silva said that laboratory technicians can't always get data from nuclear DNA.

"We only have one nucleus in the cell with 23 pairs of chromosomes," she said. "But yet, we have thousands of mitochondria in our cells."

In cases where the evidence is too degraded, most likely it won’t be possible to get any nuclear DNA profile.

"But due to the number of mitochondria in a cell, it is more likely that we can retrieve a mitochondrial DNA profile," she said.

The tests itself are different, too.

When doing nuclear DNA analysis, technicians look for specific regions in the DNA that have a sequence that repeats many times. In a mtDNA analysis, technicians usually look at the sequence of a region called control region.

However, mtDNA analysis still has limitations.

"This does not mean that we can get mito results for any level of evidence degradation," Silva said. "There are limitations to the current DNA tests that we have, so it can happen that an evidence is so degraded that we can’t really get a mtDNA profile, or we only get a partial one, which may not be enough to be linked to any individual."

Also, once you have a sequence of mtDNA, your results aren't instantly linked to a specific person.

Since mtDNA belongs to a shared group of people, technicians must compare results to a reference samples to find a match.

"You need to gather different types of evidence to link the mitochondrial DNA to a person," Silva said.

Gilgo Beach Killings

In addition to the three sex workers, Heuermann is a suspect in the death of Maureen Brainard-Barnes, whose remains were found in proximity to Costello, Barthelemy and Waterman. Together, they are known as the "Gilgo Four."

When female hairs were discovered on the remains of Brainard-Barnes, Costello and Waterman, investigators determined that they corresponded to a “Caucasian head hair fragment” but considered "not suitable" for nuclear DNA profiling at that time, court documents said.

Silva said that without knowing exactly what the evidence was like, it is difficult to say why it is described as "not suitable," but suggests they may have been "too degraded" from the elements.

"At the time the technology that we had was not advanced, so it limited the chances of getting a nuclear DNA profile from highly degraded samples or samples with very low DNA quantities," she said.

Also, the root of a hair contains better nuclear DNA quality and abundance, Silva said. Degradation of nuclear DNA has been shown to happen during the formation of the hair shaft by different studies.

"If what they found was shed hair, then nuclear DNA was most likely degraded," she said.

Bottles And Pizza

On July 21, 2022, undercover officers retrieved 11 bottles in front of Heuermann's home in a trash receptacle, left out for collection. Investigators swabbed the bottles, obtaining a DNA profile of Heuermann's wife, court documents said.

The swabs of Heuermann's wife were then matched with the female hairs found on the women's remains.

Silva said that based on this evidence alone, investigators wouldn’t be able to say for sure that the DNA belonged to his wife because it is shared by individuals of the same maternal lineage, and probably combined these results with other investigational evidence in the case.

The hair revealed caucasian/European characteristics, but was also considered unsuitable for further DNA analysis.

It wasn't until July 31, 2020, that the Suffolk County Crime Laboratory was able to generate a DNA profile for the hair recovered on the bottom of the Waterman burlap.

On Jan. 26, a surveillance team recovered a pizza box thrown out by Heuermann in Manhattan. A swab taken from the pizza crust matched the DNA from the hair found in the burlap.

On June 12, the lab matched the mtDNA profile from the pizza with the mtDNA of the hair.

Future Of Mitochondrial Analysis In Forensic Investigations

Silva told Patch that mtDNA analysis has been used for a while.

In 1996, it was first used in the United States in the murder prosecution case of Tennessee vs. Paul Ware.

"But the technology back then was not as good as today," Silva said. "So maybe the hair (found in the Gilgo Beach Killings) were too degraded that a usable mitochondrial sequence could not be obtained with the older technology."

Now, Silva said forensic scientists have Next-Generation Sequencing, for example, that has a higher sensitivity than previous technology, and could have been what investigators used in this case.

On Tuesday, Heuermann's DNA was entered into a statewide database to see if it matches any other unsolved crimes, according to a report.

At a news conference on Friday, Suffolk County Police Commissioner Rodney Harrison said that the investigation into the Gilgo Beach killings isn't over.

"Even with this arrest, we're not done," he said. "There's more work to do in this investigation regarding the other victims, the Gilgo Beach bodies that were discovered."

He also encouraged anyone with more information to call the Gilgo Beach hotline: 1-800-220-TIPS or to submit at tip on the Gilgo News website.