For illustrative purposes only
For the first time in the U.S., an identical twin has been convicted of a crime based on DNA analysis.
The breakthrough came from Parabon Nanolabs, who’s scientists used deep whole genome sequencing to identify extremely rare “somatic mutations” that differentiated Russell Marubbio and his twin, John. The results were admitted as evidence in court, making last week’s conviction of Russell in the 1987 rape of a 50-year-old woman a landmark case.
Case background
On Dec. 19, 1987, the victim, a 50-year-old woman, was working as a clerk at a gas station in Woodbridge, Va. She left the store to use the restroom, which was located outside of the building. After she entered the bathroom, a white male entered the bathroom with a knife, taped her head and hands, and raped her.
A sexual assault kit was collected at the hospital and submitted to the Department of Forensic Science (DFS). A male DNA profile was developed; however, no match for the DNA was found. With no witnesses or other evidence, the case went cold.
In 2019, detectives reopened the case as part of the Cold Case Unit, with a specific focus on using modern advanced forensic science and investigative techniques.
First, the detectives resubmitted physical evidence from 1987 to the Virginia Department of Forensic Science (DFS) for modern DNA testing to see if additional leads could be developed. DFS was able to develop a male DNA profile from the kit.
The detectives also sent part of the victim’s underwear to Marshall University Forensic Science Center to extract DNA information for genetic genealogy analysis. This analysis came back to twins—John Arthur Marubbio of Deltona, Fla., and Russell Anthony Marubbio of Palatka, Fla.
Modern DNA analysis
Enlisting the help of Florida special agents, the detectives were able to obtain buccal swabs from both brothers to compare their individual DNA to the profile developed from the evidence. Unsurprisingly, their individual DNA matched the items seized at the time of the crime, however, could not differentiate between the identical twins.
Then, in August 2022, the Prince William County detectives turned to Parabon NanoLabs and its laboratory partners for help. Parabon’s scientists had an idea—let’s look for somatic mutations between the twins.
Somatic mutations are DNA changes that happen after conception and can cause genetic differences between otherwise identical twins. These mutations can arise during the earliest stages of embryonic development, affecting the split of the zygote, and accumulate throughout life due to errors in cell division. Somatic mutations can be present in only one twin, a subset of cells, or both, potentially leading to differences in health and even developmental disorders—and in this case, DNA.
The science behind somatic mutations is not new, and is well-researched, understood and accepted. It’s just uncommon for DNA to lead to twins, and even more uncommon for somatic mutations to be able to distinguish between twins.
In a 2017 case in Massachusetts, researchers used next-generation sequencing (NGS) to distinguish between twin suspects. However, the judge on that case ruled the evidence as inadmissible as NGS was still in its infancy at that time. That changed in January 2024 when, for the first time in the U.S., evidence derived from NGS was accepted in a court of law.
In the Marubbio case, Parabon scientists used deep whole genome sequencing and specialized bioinformatics analysis to identify unique somatic mutations in each twin. They then compared that directly to the DNA recovered from the crime scene. This conclusively identified Russell Marubbio as the twin whose DNA was present at the crime scene.
Much like the January 2024 case for NGS, the Marubbio case now becomes a landmark for whole genome sequencing and DNA analysis.
“This was a 38-year-old rape case that had long been forgotten about by everyone except the victim, who has had to live with the fear and pain of having been raped, and without any closure on this case until now,” said Prince William County Commonwealth’s Attorney Amy Ashworth.