Case Watch · Police Practices
The Matthew Nilo case isn’t putting forensic genetic genealogy on trial — it’s putting the investigative process behind it under a microscope. What investigators knew before confirmatory DNA was collected, and whether that process can be reconstructed, is where the defense is digging.
By Christine Burke · 2026-08-22 · 12 min read
The Matthew Nilo case is turning into one of those cases law enforcement should be watching very closely.
Not because forensic genetic genealogy is somehow on trial.
It isn't.
And not because the FBI's collection of DNA from restaurant items has already been ruled unlawful. It hasn't.
What makes this case interesting is where the defense is attacking the investigation.
They're going after the gap between:
FGG gave investigators a name
and
the confirmatory DNA proved the name was right.
That gap matters.
A lot.
Nilo is accused of multiple sexual assaults in Boston in 2007 and 2008. He has pleaded not guilty.
Investigators had male DNA from the original sexual-assault evidence. The profiles connected multiple crimes, but CODIS never identified the contributor.
Years later, the investigation was reopened and forensic genetic genealogy was used.
According to the Commonwealth, investigators developed an SNP profile, searched genealogy databases, identified genetic relatives, conducted reference testing, built a family tree and eventually identified Matthew Nilo as the likely contributor of the DNA recovered from one of the assaults.
Then came the confirmation phase.
On April 6, 2023, FBI agents followed Nilo from New Jersey into Manhattan and watched him at the Oscar Wilde restaurant. Agents obtained drinking glasses and other items he had used. After the group left, other items were collected from the table, including a fork, a glass and a napkin.
DNA was recovered.
The STR comparison allegedly matched the unknown male profile from the Boston sexual-assault evidence.
That's incredibly strong evidence.
But here's where the case gets interesting.
Nilo's defense is asking the court to look at what happened before that match existed.
And from a police-practices standpoint, that's where the weak spot may be.
Once you know the confirmatory DNA matched, it's really easy to look backward and think the investigation was obviously right.
Of course they had the right guy.
The DNA proved it.
But that isn't the question Nilo is raising.
His argument focuses on what investigators knew at the time they deliberately went after his biological material.
Strip out the later STR result for a minute.
What was left?
They had a DNA-linked series of sexual assaults.
They had an SNP profile developed from crime-scene evidence.
They had genealogy matches.
They had relatives.
They had reference testing.
They had a family tree.
And the FGG work apparently led investigators to conclude that Nilo was the likely contributor.
There was also some traditional corroboration. His age generally fit. He had ties to the Boston area during the relevant period. Prosecutors have pointed to the college calendar and other circumstances suggesting he could have been in Boston when the crimes occurred.
That's not nothing.
But it also isn't the same thing as the later STR match.
And that distinction is exactly where the defense is digging.
This is something I see over and over in FGG cases.
A report says:
"Forensic genetic genealogy identified John Smith as the suspect."
That's a really loaded sentence.
What does "identified" mean?
Did the genealogy narrow the family down to one biological male?
Were there three brothers?
Two cousins?
Was somebody eliminated because of age?
Because of geography?
Because of records?
Because of reference testing?
Because somebody made an assumption about a relationship?
Did investigators independently verify those eliminations?
Or did the FGG process simply put one person at the top of the list?
Those are very different situations.
FGG is an investigative process. Sometimes a messy one.
You can have good matches, bad trees, missing fathers, half relationships, pedigree collapse, endogamy, inaccurate public trees, adoption, non-paternity events and people who just disappear from the paper trail.
A clean little sentence in a police report can make all of that look much more certain than it actually was at the time.
That's where a defense attorney can start pulling threads.
One of the Massachusetts cases cited by the defense is Commonwealth v. Trigones.
Trigones wasn't an FGG case.
It involved a compelled blood sample.
But the language matters.
Before the government obtained Trigones's blood, investigators had evidence connecting him specifically to biological evidence associated with the murder. He had fresh cuts. There was blood associated with his vehicle. There was unknown blood connected to the crime.
The Massachusetts Supreme Judicial Court said the Commonwealth had to show that the blood sample would "probably produce evidence relevant to the question of the defendant's guilt."
Nilo is trying to apply that thinking to his case.
Basically:
What did investigators know about Matthew Nilo before they went after his DNA that made his biological material likely to produce evidence of these crimes?
The Commonwealth has an obvious answer.
The FGG investigation.
And that's exactly why the FGG work itself suddenly becomes so important.
Think about the chain.
Crime-scene DNA.
SNP profile.
Genealogy databases.
Genetic matches.
Family tree.
Reference testing.
Nilo identified as the likely contributor.
Then the FBI goes out and gets his DNA.
If the prosecution is relying on that chain to explain why agents targeted Nilo specifically, the defense is going to want to know what happened inside it.
How strong were the matches?
How was the tree built?
Who else fit?
How were other candidates eliminated?
What did the reference testing actually establish?
What assumptions were made?
What was independently verified?
Who did the work?
What records were kept?
What disappeared after the investigation was completed?
That's not some side issue anymore.
It potentially becomes part of the explanation for why police were looking at this guy in the first place.
This is where DNA cases can get a little backwards.
Once the STR result comes back, the case looks fantastic.
The person FGG pointed to is now directly connected to the crime-scene DNA.
Great.
But if the collection itself gets challenged, the later match doesn't answer every question about what happened before it.
You can't simply say:
"Well, obviously we had good reason to get his DNA because it matched."
That's hindsight.
From a police-practices standpoint, the cleaner question is:
What did the investigation look like the day before the confirmation sample existed?
That's where the genealogy work and traditional detective work either hold up or they don't.
FGG may get you to a family.
It may get you to a branch.
Sometimes it gets you very close to one person.
But the traditional investigation still matters.
In the Nilo case, age matters.
Residence matters.
The crime dates matter.
The fact that he was attending college out of state matters.
The school calendar matters.
Where he was actually living during breaks matters even more.
Victim descriptions matter.
Vehicles matter.
Connections to Terminal Street matter.
Anything tying him to one of the victims, the location or the circumstances of the crimes matters.
And the stuff that doesn't fit matters too.
If somebody's alibi is solid, that matters.
If a brother fits the genealogy just as well but nobody really eliminated him, that matters.
If the only thing putting Nilo above another relative was an assumption in the family tree, that matters.
FGG doesn't make those questions disappear.
The Nilo investigation reportedly included relatives who consented to reference testing.
That can be extremely useful.
But it can also make the pathway to the suspect more complicated.
If a relative's DNA was what allowed investigators to move from a broad family to a much narrower branch, that result may become part of the defense's challenge to the FGG process.
Who was tested?
Why that person?
What relationship was expected?
What relationship did the DNA actually support?
What did the result eliminate?
Did it eliminate people genetically, or did it just make one theory more likely?
Were those reference samples preserved?
Were the reports preserved?
Was the reasoning written down?
Those details can start looking a whole lot more important when a suppression motion lands.
The Commonwealth has said that after Nilo's arrest and charging, the SNP profile was removed from the genealogy services and associated information became inaccessible.
That should get everybody's attention.
There may be legitimate privacy policies, database rules or DOJ requirements requiring certain information to be removed.
That's not the issue.
The issue is what happens when the defense later says:
"You are telling the court that this FGG investigation was the reason law enforcement targeted my client, but now nobody can reproduce exactly how that conclusion was reached."
That's not a great place for a prosecution to be.
Screenshots.
Match lists.
Research notes.
Trees.
Relationship hypotheses.
Reference-test results.
Candidate lists.
Eliminations.
Emails.
Vendor communications.
Who did what.
What policies were in effect.
What was deleted.
When it was deleted.
Why it was deleted.
Those things may end up mattering a lot more than agencies expected when the case was first solved.
There's a huge difference between:
"FGG identified Smith as the perpetrator."
"FGG generated Smith as an investigative lead."
Then the traditional investigation happened.
Then the confirmatory DNA was collected.
Then the STR comparison was performed.
That chronology is cleaner because it's actually describing what happened.
FGG is usually generating a lead.
The direct forensic comparison comes later.
Blurring those two stages may make the case sound stronger in a press release, but it can create problems once lawyers start picking apart what investigators knew and when they knew it.
Police have been collecting discarded DNA forever.
Cigarette butts.
Cups.
Straws.
Tissues.
Trash.
That's not new.
What is getting more interesting in FGG cases is how intentional the collection can be.
The police aren't necessarily stumbling across somebody's discarded cup.
They may be following a person because an FGG investigation pointed specifically to that person and waiting for an opportunity to obtain biological material for confirmation.
That's different factually.
Whether courts decide it is different constitutionally is another question.
That's part of what makes Nilo worth watching.
In his case, FBI agents followed him into a restaurant, watched what he used and obtained specific items associated with him.
The defense is arguing that this wasn't ordinary abandoned property. They're characterizing it as a deliberate government effort to obtain his biological material without a warrant.
The prosecution says he relinquished the items and had no protected privacy interest in them.
That's the fight.
And agencies using FGG should probably assume we're going to see more of it.
I'm not saying police always need a warrant for discarded DNA.
That's not the law.
But I do think the Nilo case raises a practical question agencies are going to have to wrestle with.
If the FGG case is already strong enough that investigators genuinely believe one person is the contributor, and traditional police work has independently backed that up, at what point does seeking judicial authorization make more sense than creating another suppression issue?
Sometimes there won't be probable cause yet.
Sometimes the abandoned-property route will be perfectly lawful.
Sometimes getting a warrant may not be practical.
Every case is different.
But if the FGG investigation is the entire reason you're targeting one person's biological material, the legal basis for that collection deserves more thought than:
We've always picked up cups.
The technology and the investigative process around it have changed.
The litigation is catching up.
We already know FGG works.
The Nilo case is about something else.
Can the investigative process behind it be reconstructed?
Can investigators explain why one person was selected?
Can they separate what the genealogy suggested from what was later confirmed?
Can they show what was independently corroborated?
Can they explain who else fit and why those people were eliminated?
Can they account for the reference testing?
Can they produce the documentation?
Can they explain why the confirmation sample was collected the way it was?
Those are police-practices questions.
And those are the questions I think are going to start showing up more often as defense attorneys become more familiar with forensic genetic genealogy.
There was a period where just hearing the words "genetic genealogy" sounded almost mystical in court.
That period is ending.
Defense attorneys are learning the process.
They're learning the terminology.
They're asking for the trees.
They're asking about the matches.
They're looking at reference testing.
They're looking at database policies.
They're looking at preservation.
And now they're looking very closely at the confirmatory DNA step.
That's where the Matthew Nilo case has my attention.
Because if the court starts putting more scrutiny on what law enforcement knew before confirmatory DNA was collected, agencies may have to rethink how they document the handoff between FGG and traditional investigation.
The forensic genetic genealogy may have found exactly the right person.
That doesn't mean the rest of the case can't get sideways.
And that's the part I don't want agencies finding out about for the first time during a suppression hearing.
I work with law-enforcement agencies on forensic genetic genealogy, case strategy, investigative workflow, documentation, training and case review.
If your agency is already using FGG, building an internal program, or you're looking at an FGG case and wondering whether there are holes in the investigative or confirmation process, that's exactly the kind of work I do.
I'd rather look at it before the defense does.
Christine Burke Forensic Genetic Genealogist | Law Enforcement Trainer | Police Practices Expert Genetic Genealogy for Law Enforcement
This article is for law-enforcement training and educational purposes. The constitutional issues in the Matthew Nilo case remain contested, and the court has not ruled that the challenged DNA collection was lawful or unlawful. Agencies should consult their prosecutors and legal counsel regarding the facts of individual investigations and applicable federal and state law.
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