METHOD

How the FBI Traced $3.6B in Bitcoin — Tool by Tool

In August 2016, 119,754 BTC was stolen from the Hong Kong cryptocurrency exchange Bitfinex. The funds moved through thousands of addresses over six years — mixers, chain hops, darknet markets. In February 2022, the FBI recovered 94,636 BTC in 133 minutes and swept everything into a single custody address. That address has not sent a single satoshi since.

This is a walkthrough of looking it up. The same address queried across four tools, with four different results. Then a trace on one transaction that pulls a thread from the seizure back to a staging address funded 13 days before the theft happened.

The address

FBI custody address
bc1qazcm763858nkj2dj986etajv6wquslv8uxwczt
Balance
94,643.49 BTC
~$6.4 billion USD
Transactions
175 received
0 sent
Format
Bech32 P2WPKH
Native SegWit
Wallet cluster
9d2530c104
FBI 3 — per blockchain intelligence labelling

The label "FBI 3" does not exist on the Bitcoin blockchain. It was assigned by blockchain intelligence firms tracking the seizure. The address itself is a string of characters with no name attached. The label lives in the analytical layer built on top of the protocol — and which tool you use determines whether you see it at all.

Four tools, four different experiences

Tool Data returned Observer Notes
Blockchair Full data, heavy noise Blockchair Balance and history present. Page carries gambling ads and embedded commercial AML scoring.
3xpl (clearnet) Full data, clean 3xpl 175 transactions, live balance, USD value. No ads, no commercial overlays.
3xpl (.onion) Full data, clean Nobody Identical result via Tor hidden service. Query does not reach 3xpl servers.
blockchain.com API Raw JSON, no auth Blockchain.com blockchain.info/rawaddr/[address] — complete data, no account required. 100 transactions per call.
WalletExplorer Full data + clustering Chainalysis Wallet grouping, labelled addresses, CSV export. Creator now works at Chainalysis — stated on the site.

Blockchair: data inside a commercial layer

Blockchair returns the address without issue. Balance, USD equivalent, full transaction history. The data is accurate.

What surrounds it requires attention. The page loads with gambling promotions alongside a "dApp Gallery" panel embedding commercial analytics products. A third-party AML risk score rates the address at 15 out of 100. Further widgets offer sanctions screening and paid wallet statement generation.

Blockchair showing bc1qazcm address with balance 94,643 BTC and surrounding gambling ads and AML widgets
Blockchair. Balance: 94,643.48819655 BTC / $6,445,624,727 USD. Most recent transaction 9 hours prior at time of capture. The page also serves gambling promotions and embeds commercial AML scoring. A risk score of 15/100 on a known FBI custody wallet is a product being sold, not an analytical finding.

None of this invalidates the data. But the commercial layer shapes how a researcher reads a result, and the AML scores on that panel are not independent analysis — they are products from third-party vendors paying for placement.

3xpl: the same data without the layer

3xpl was founded by former Blockchair developers. The editorial approach is similar; the commercial model is not. The address page loads cleanly: balance, transaction count, full history, USD value. No ads, no embedded third-party tools, no risk scoring.

3xpl showing bc1qazcm address with 175 transactions and balance 94,643.48819655 BTC at $6,424,207,852.50 USD
3xpl (clearnet). 94,643.48819655 BTC / $6,424,207,852.50 USD. 175 transactions. The most recent — Mar 8, 2026 at 00:51 UTC, +0.00000294 BTC, $0.19 — arrived while this investigation was running.

3xpl operates a Tor hidden service at 3xplor3rzajysy4j5fi3g3k27vivfcw75zjxdb2tg2wpz3i4cdiyhxyd.onion. The same address navigated to via that URL returns identical data. The operational difference is that the query terminates within the Tor network — 3xpl's servers receive no IP, no timestamp, no log of the lookup.

3xpl .onion address showing the same FBI3 wallet data accessed via Tor browser
3xpl via Tor (.onion). Same address, same balance, same transaction list. The browser address bar shows the .onion URL. The query never left the Tor network. The USD value differs slightly from the clearnet screenshot — the BTC price moved between the two lookups.

The blockchain.com API

The blockchain.com website is friction-heavy by design. Sign-in prompts appear on address pages. Addresses truncate in the UI. Transaction lists paginate without obvious export paths.

The API behind it has none of these constraints. The endpoint https://blockchain.info/rawaddr/bc1qazcm763858nkj2dj986etajv6wquslv8uxwczt returns a complete JSON object with no authentication. Total received: 9,464,348,819,655 satoshis — 94,643.48819655 BTC. Total sent: 0. 174 transactions on record at time of query, 100 returned per call, the remainder retrieved with an offset parameter.

Most researchers using the browser interface do not know the API exists. The underlying data is identical. The access path is just not surfaced.

WalletExplorer: clustering and the Chainalysis connection

WalletExplorer groups addresses into wallets using co-spending heuristics — the principle that inputs appearing in the same transaction were likely controlled by the same entity. The FBI3 address belongs to cluster 9d2530c104. The cluster view shows all associated addresses, including several labelled CoinJoinMess — WalletExplorer's annotation for addresses associated with CoinJoin mixing transactions, part of the obfuscation layer used in the laundering operation.

WalletExplorer showing bc1qazcm as part of wallet 9d2530c104, 173 total transactions with CSV export
WalletExplorer — address view. Identified as part of wallet 9d2530c104. 173 transactions. CSV export available. The footer states: "The author of WalletExplorer.com now works there as an analyst and programmer" — linking directly to Chainalysis.com.
WalletExplorer wallet cluster 9d2530c104 showing full address list with CoinJoinMess labels
WalletExplorer — wallet cluster 9d2530c104. All addresses associated with the FBI3 custody wallet. Several sending addresses carry the CoinJoinMess label — the mixing layer that preceded the seizure, still visible in the cluster record.

The operational consideration is what happens to the lookup itself. WalletExplorer's creator now works at Chainalysis — the dominant blockchain intelligence firm under contract with the FBI, IRS Criminal Investigation, DEA, and Europol. Using WalletExplorer on clearnet logs your IP against the address you queried. That log sits with an entity whose commercial purpose is providing investigative data to law enforcement.

The lookups for this investigation were conducted via WalletExplorer's Tor hidden service.

Following the transaction chain

The consolidation on February 1, 2022 began at 04:14 UTC with a single 1 BTC test, then proceeded in scripted batches. Transaction afdfeeadb9f0 — the first major sweep at 04:27 UTC — moved 10,000 BTC from 223 input addresses into the FBI3 wallet. Fee: 0.00420162 BTC. Roughly $160 to move approximately $400 million.

3xpl showing transaction afdfeeadb9f0: 10,000 BTC output to FBI3 wallet, change of 13.79 BTC returned to 1MiWBb
3xpl — transaction afdfeeadb9f0. Two outputs: 10,000 BTC to the FBI3 custody address, and 13.79062700 BTC returned as change to 1MiWBbynejkA7LG7x1x7GZaiCeKCUptJPq. Block 721,286.

The change output — 13.79062700 BTC to 1MiWBbynejkA7LG7x1x7GZaiCeKCUptJPq — is the remainder from the sweep, returned to a staging address for collection in the next pass 84 minutes later. Looking up that address returns its complete transaction history on a single screen.

3xpl showing 1MiWBb address: 4 transactions, received 109 BTC Aug 2016, zero balance
3xpl — staging address 1MiWBbynejkA7LG7x1x7GZaiCeKCUptJPq. Four transactions. Received 109.02740674 BTC on Aug 2, 2016. Spent across two transactions on Feb 1, 2022. Balance: zero. The address was active for a single morning in 2016, then dormant for 2,009 days.

The first transaction on that address links to transaction 01c7cdfe8ff2 — dated August 2, 2016, 09:13 UTC. The date of the Bitfinex hack.

3xpl showing transaction 01c7cdfe: Aug 2 2016, inputs from 35etn and 3C82 addresses, 109 BTC output to 1MiWBb
3xpl — transaction 01c7cdfe8ff2. August 2, 2016, 09:13 UTC. Inputs include 35etnSCUjBh9DAqziMrpxN5CQA89S7Bc8p contributing 82.53 BTC and 3C82brP79vePuRJPCw611mcqymU9NZZrv2 — the Bitfinex hot wallet. Output: 109.02740674 BTC to 1MiWBbynejkA7LG7x1x7GZaiCeKCUptJPq. This is the theft transaction.

One of the inputs — 35etnSCUjBh9DAqziMrpxN5CQA89S7Bc8p — spent 82.53001252 BTC into that transaction. Looking it up shows a two-transaction address with a zero balance. Its entire history fits in four rows.

3xpl showing 35etn address: received 82.53 BTC on Jul 20 2016, spent Aug 2 2016, zero balance
3xpl — pre-staging address 35etnSCUjBh9DAqziMrpxN5CQA89S7Bc8p. Received 82.53001252 BTC on July 20, 2016. Spent in full on August 2, 2016 — the day of the hack. Two transactions, zero balance, never used again.

This address was funded on July 20, 2016 — 13 days before the theft. The funding transaction, 4a250b22fc42, shows the source: 3C82brP79vePuRJPCw611mcqymU9NZZrv2, the same Bitfinex hot wallet address that appears as an input in the hack transaction itself.

3xpl showing transaction 4a250b: Jul 20 2016, input from 3C82 Bitfinex hot wallet, output of 82.53 BTC to 35etn staging address
3xpl — transaction 4a250b22fc42. July 20, 2016, 19:16 UTC. Input: 3C82brP79vePuRJPCw611mcqymU9NZZrv2 spending 108.96 BTC. Output: 82.53001252 BTC to 35etnSCUjBh9DAqziMrpxN5CQA89S7Bc8p. The attack infrastructure was funded from Bitfinex's own hot wallet 13 days before the theft executed.

The full chain, reconstructed from public data:

Trace — July 2016 to February 2022
2016-07-20 4a250b22fc42 — Bitfinex hot wallet 3C82brP79ve funds staging address 35etn… with +82.53 BTC. Attack infrastructure pre-positioned 13 days before the theft.
↓    13 days    ↓
2016-08-02 01c7cdfe8ff235etn… and hot wallet 3C82brP79ve spend together. Output: +109.02740674 BTC to staging address 1MiWBb…. This is the theft transaction.
↓    2,009 days of dormancy    ↓
2022-02-01 04:27 afdfeeadb9f0 — first major FBI sweep. −95.24 BTC from 1MiWBb… into FBI3 custody wallet. Change: 13.79 BTC returned.
2022-02-01 05:51 e6088723889d — remaining 13.79 BTC swept. 1MiWBb… balance: zero. Address never used again.

The staging address 35etn was funded from Bitfinex's own hot wallet 13 days before the hack. The attacker had access to move funds out of the exchange before the theft executed. The public record has contained this detail since August 2, 2016. Finding it required following two transactions back from the seizure.

The consolidation

The full February 1 sweep comprised 22 transactions across 133 minutes. A test transaction at 04:14, then batches of increasing size in parallel, ending with a dust pass collecting fractional remainders from 510 addresses simultaneously.

Consolidation — February 1, 2022 (UTC)
04:14:24 +1 BTC Test transaction. Single input. Confirms the custody address before large sums move.
04:27:57 +10,000 BTC First major sweep. 223 inputs. Transaction afdfeeadb9f0. Fee: 0.00420162 BTC (~$160).
04:57:22 +15,000 / +15,000 / +10,000 BTC Three transactions submitted simultaneously. 35,000 BTC in a single block submission.
05:51:13 +10,000 ×4, +2,500, +2,000, +100, +20 BTC Eight transactions in the same minute. Scripted batch execution.
06:27:07 +0.29837084 BTC Dust sweep. 510 input addresses. Every fractional remainder collected in a single pass.

The FBI did not crack Lichtenstein's encryption. They found the keys — stored in an encrypted file on cloud storage that agents accessed. The six-year laundering operation held technically. The storage decision did not.

The dust record

The FBI3 wallet received 153 transactions after the consolidation. Every one is under 0.001 BTC. These are analyst tracking tags — small amounts sent to anchor an address in a monitoring system, or to associate it with a researcher's own address for later graph analysis. The first arrived on February 2, 2022, one day after the seizure. The community was watching before the arrests were announced on February 8.

During this investigation, the most recent transaction on the 3xpl address page — Mar 8, 2026, 00:51 UTC, +0.00000294 BTC, $0.19 — arrived while the lookup was running. The wallet is watched continuously. The blockchain does not distinguish between who is watching.

What the trace demonstrates

Starting from the FBI3 custody wallet, two hops back through the transaction graph reached a staging address funded from Bitfinex's own hot wallet on July 20, 2016 — 13 days before the theft. The entire chain is in the public record. It was always there. Finding it required choosing the right tool and following the transactions.

This is what blockchain transparency means in practice. The data is permanent and complete. The variable is the analytical layer: which tools surface it, whether the addresses carry labels, and what those tools do with the fact that you queried them. The same address across four tools returned four different experiences of the same public record.

The methodology that broke the case was not purely the blockchain component. Lichtenstein's laundering held technically for six years. What collapsed it was the intersection of digital behaviour with ordinary commercial infrastructure: an encrypted file in cloud storage found by agents with account access. And separately — Heather Morgan redeeming a Walmart gift card with her real name, linked to a loyalty programme, linked to a darknet forum registration, linked to a cryptocurrency address. $9.4 billion concealed across 2,009 days. Ended by a receipt.

The same cross-referencing approach — loyalty programme records, commercial transaction data, corporate registry filings, data broker profiles — is what a personal exposure audit runs against a name. The blockchain is one axis. It is rarely the only one.

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