Bitcoin's big secret: How cryptocurrency became law enforcement's secret weapon

At the 2025 Bitwarden Open Source Security Summit, WIRED's Andy Greenberg sat down for a fireside chat with GigaOm analyst Paul Stringfellow to discuss a revelation that turned his decades-long reporting on its head: Bitcoin became a criminal's worst nightmare.

In 2011, Greenberg thought he'd discovered the story of a lifetime: digital cash that promised complete anonymity. A decade later, that story flipped entirely.

"I had this slow-motion epiphany that I was entirely wrong about Bitcoin. It was, in fact, the opposite of untraceable."

Starting around 2014, law enforcement discovered something remarkable: Bitcoin's blockchain was a permanent, traceable record.

Enter Tigran Gambaryan, an IRS criminal investigator who would become the hero of Greenberg's book Tracers in the Dark. The same IRS unit that brought down Al Capone for tax evasion now had a new weapon: blockchain forensics. Working alongside cryptocurrency tracing startup Chainalysis, Gambaryan developed techniques that offered even greater transparency than traditional financial systems.

"They could follow the money with even greater financial forensic power than in the traditional finance system."

The scale of what followed was staggering. Greenberg walked through several landmark cases that reshaped how law enforcement thinks about cryptocurrency:

• Silk Road's corruption: Corrupt DEA and Secret Service agents received Bitcoin payments from the site's kingpin. Blockchain analysis proved these weren't personal investments — they were payments to moles selling law enforcement secrets.

• Mt. Gox heist: Investigators traced 650,000 stolen Bitcoins to Russian cybercriminals, leading to arrests when one vacationed in Greece.

• AlphaBay: Federal agents dismantled this dark web drug marketplace after cryptocurrency tracing identified kingpin Alexandre Cazes operating from Bangkok. Advanced crypto techniques revealed the secret server's location in Lithuania.

• Welcome to Video: Blockchain analysis exposed a dark web marketplace for child sexual abuse materials (CSAM). Investigators identified 337 perpetrators worldwide and rescued 23 children.

"The first, second, and third biggest seizures of money in US Justice Department history — billions of dollars."

Gambaryan and his colleagues carried out the first, second, and third largest financial seizures in U.S. Justice Department history. Not just in cryptocurrency — in any crime category, period.

But here's the paradox: if cryptocurrency tracing is so powerful, why do ransomware attacks, pig butchering scams, and North Korean hackers continue to steal billions?

The answer: identifiability isn't the same as accountability.

• Law enforcement can identify perpetrators with incredible accuracy through blockchain analysis

• But criminals operating from Russia, North Korea, or lawless Southeast Asian zones remain out of reach

• Ransomware profits dropped significantly last year when federal investigators seized websites and cryptocurrency — even without arrests

• Pig butchering scams steal tens of billions annually through forced labor compounds, yet Chinese crime bosses face minimal consequences

• The gap: law enforcement hasn't prioritized crypto tracing investigations against scam operations at scale

"You can identify perpetrators with incredible accuracy thanks to the blockchain, but if they're beyond the reach of Western law enforcement, they can still be beyond accountability."

As the discussion wrapped up, Stringfellow highlighted a provocative tension: while blockchain analysis empowers law enforcement, it also raises profound privacy concerns for everyone else. The same technology that catches criminals can potentially track law-abiding citizens, making this book more than just a true crime thriller.

"When you read this book, you realize how cool accountants are."

Forensic accountants power the most exciting detective work of the digital age. They analyze blockchain transactions, where hackers and traditional law enforcement often hit dead ends.

Tracers in the Dark is now available and offers a comprehensive deep dive into these cases and the forensic techniques that led to their resolution.

For anyone interested in cybersecurity, cryptocurrency, or the intersection of technology and crime, the full fireside chat delivers cases that read like spy novels but are entirely real. Hear directly from Greenberg about covert operations, international manhunts, and the complete reversal of what criminals thought they knew about staying anonymous online.