diff --git a/poseidon-tornado/src/main.rs b/poseidon-tornado/src/main.rs
index e6e3a18..7366d21 100644
--- a/poseidon-tornado/src/main.rs
+++ b/poseidon-tornado/src/main.rs
@@ -13,6 +13,21 @@ use num_bigint::BigInt;
 use serde::Deserialize;
 use serde_json;
 
+// XXX look over
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct WitnessInput {
+    root: String,
+    nullifier_hash: String,
+    recipient: String,
+    relayer: String,
+    //fee: String,
+    fee: i32,
+    nullifier: String,
+    path_elements: Vec<String>,
+    path_indices: Vec<i32>,
+}
+
 #[derive(Debug, Deserialize)]
 #[serde(rename_all = "camelCase")]
 struct DepositInput {
@@ -28,6 +43,175 @@ struct DepositInput {
     path_indices: Vec<i32>,
 }
 
+
+
+// Poseidon-tornado
+fn groth16_proof_example() -> Result<()> {
+    println!("Circom 1");
+
+    // Tracing to help with debugging
+    let mut layer = ConstraintLayer::default();
+    layer.mode = TracingMode::OnlyConstraints;
+    let subscriber = tracing_subscriber::Registry::default().with(layer);
+    let _guard = tracing::subscriber::set_default(subscriber);
+
+    let trace = ConstraintTrace::capture();
+    println!("Trace is: {:?}", trace);
+
+    let cfg = CircomConfig::<Bn254>::new(
+        "./resources/withdraw.wasm",
+        "./resources/withdraw.r1cs",
+     )?;
+
+    // Test
+    let trace = ConstraintTrace::capture();
+    println!("Trace is: {:?}", trace);
+
+    // XXX: Weird mix here
+    // From poseidon-tornado JSON witness
+    let input_json_str = r#"
+{
+  "root": "17777834528943231885798890273562835075271930126129561600279382876922601684948",
+  "nullifierHash": "8506691148847834795277894036216352001616813487121834991716343668271924769133",
+  "recipient": "344073830386746567427978432078835137280280269756",
+  "relayer": "0x70997970C51812dc3A010C7d01b50e0d17dc79C8",
+  "fee": 0,
+  "nullifier": "0",
+  "pathElements": [
+    "21663839004416932945382355908790599225266501822907911457504978515578255421292",
+    "8995896153219992062710898675021891003404871425075198597897889079729967997688",
+    "15126246733515326086631621937388047923581111613947275249184377560170833782629",
+    "6404200169958188928270149728908101781856690902670925316782889389790091378414",
+    "17903822129909817717122288064678017104411031693253675943446999432073303897479",
+    "11423673436710698439362231088473903829893023095386581732682931796661338615804",
+    "10494842461667482273766668782207799332467432901404302674544629280016211342367",
+    "17400501067905286947724900644309270241576392716005448085614420258732805558809",
+    "7924095784194248701091699324325620647610183513781643345297447650838438175245",
+    "3170907381568164996048434627595073437765146540390351066869729445199396390350",
+    "21224698076141654110749227566074000819685780865045032659353546489395159395031",
+    "18113275293366123216771546175954550524914431153457717566389477633419482708807",
+    "1952712013602708178570747052202251655221844679392349715649271315658568301659",
+    "18071586466641072671725723167170872238457150900980957071031663421538421560166",
+    "9993139859464142980356243228522899168680191731482953959604385644693217291503",
+    "14825089209834329031146290681677780462512538924857394026404638992248153156554",
+    "4227387664466178643628175945231814400524887119677268757709033164980107894508",
+    "177945332589823419436506514313470826662740485666603469953512016396504401819",
+    "4236715569920417171293504597566056255435509785944924295068274306682611080863",
+    "8055374341341620501424923482910636721817757020788836089492629714380498049891"
+  ],
+  "pathIndices": [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]}
+"#;
+
+    let witness_input : WitnessInput = serde_json::from_str(input_json_str).expect("JSON was not well-formatted");
+
+    println!("JSON: {:?}", witness_input);
+
+    println!("Circom 2");
+
+    let mut builder = CircomBuilder::new(cfg);
+
+    // XXX Seems like a mix between BigInt and hex-encoded - radix 10 and 16 mixed?
+    // Especially problematic for pathElements - let's try and see
+
+    builder.push_input(
+        "root",
+        BigInt::parse_bytes(witness_input.root.as_bytes(), 10).unwrap(),
+    );
+
+    builder.push_input(
+        "nullifierHash",
+        BigInt::parse_bytes(witness_input.nullifier_hash.as_bytes(), 10).unwrap(),
+    );
+
+    builder.push_input(
+        "recipient",
+        // BigInt::parse_bytes(
+        //     witness_input.recipient.strip_prefix("0x").unwrap().as_bytes(),
+        //     16,
+        // )
+        // .unwrap(),
+        BigInt::parse_bytes(witness_input.recipient.as_bytes(), 10).unwrap(),
+    );
+
+    builder.push_input(
+        "relayer",
+        BigInt::parse_bytes(
+            witness_input.relayer.strip_prefix("0x").unwrap().as_bytes(),
+            16,
+        )
+        .unwrap(),
+    );
+
+    // XXX
+    builder.push_input(
+        "fee",
+        witness_input.fee
+        //BigInt::parse_bytes(witness_input.fee.as_bytes(), 10).unwrap(),
+    );
+
+     builder.push_input(
+        "nullifer",
+        BigInt::parse_bytes(witness_input.nullifier.as_bytes(), 10).unwrap(),
+    );
+
+    // XXX We have a mix here - conditionally push? seems smelly
+    for v in witness_input.path_elements.iter() {
+            builder.push_input(
+                "pathElements",
+                BigInt::parse_bytes(v.as_bytes(), 10).unwrap(),
+            );
+    }
+
+    for v in witness_input.path_indices.iter() {
+        builder.push_input("pathIndices", BigInt::from(*v));
+    }
+
+    // XXX
+    println!("Circom 3 - builder");
+    println!("Builder input:\n {:#?}", builder.inputs);
+
+    // but would like the tracing to tell me this
+    //
+    // what are the public inputs here
+    //
+    //  From poseidon-tornado
+    // const witness = {
+    //     // Public
+    //     root,
+    //     nullifierHash,
+    //     recipient,
+    //     relayer,
+    //     fee,
+    //     // Private
+    //     nullifier: BigNumber.from(deposit.nullifier).toBigInt(),
+    //     pathElements: path_elements,
+    //     pathIndices: path_index,
+    // };
+
+    // create an empty instance for setting it up
+    let circom = builder.setup();
+
+    let mut rng = thread_rng();
+    let params = generate_random_parameters::<Bn254, _, _>(circom, &mut rng)?;
+
+    let circom = builder.build()?;
+
+    let inputs = circom.get_public_inputs().unwrap();
+
+    println!("Inputs {:#?} ", inputs);
+
+    let proof = prove(circom, &params, &mut rng)?;
+
+    let pvk = prepare_verifying_key(&params.vk);
+
+    let verified = verify_proof(&pvk, &proof, &inputs)?;
+
+    assert!(verified);
+
+    Ok(())
+}
+
+
 // tornado-core
 fn groth16_proof_example2() -> Result<()> {
     println!("Circom 1");