diff --git a/gtsam/hybrid/HybridBayesTree.cpp b/gtsam/hybrid/HybridBayesTree.cpp
index d600714d4..8fb487ae2 100644
--- a/gtsam/hybrid/HybridBayesTree.cpp
+++ b/gtsam/hybrid/HybridBayesTree.cpp
@@ -144,4 +144,61 @@ VectorValues HybridBayesTree::optimize(const DiscreteValues& assignment) const {
   return result;
 }
 
+/* ************************************************************************* */
+void HybridBayesTree::prune(const size_t maxNrLeaves) {
+  auto decisionTree = boost::dynamic_pointer_cast<DecisionTreeFactor>(
+      this->roots_.at(0)->conditional()->inner());
+
+  DecisionTreeFactor prunedDiscreteFactor = decisionTree->prune(maxNrLeaves);
+  decisionTree->root_ = prunedDiscreteFactor.root_;
+
+  /// Helper struct for pruning the hybrid bayes tree.
+  struct HybridPrunerData {
+    /// The discrete decision tree after pruning.
+    DecisionTreeFactor prunedDiscreteFactor;
+    HybridPrunerData(const DecisionTreeFactor& prunedDiscreteFactor,
+                     const HybridBayesTree::sharedNode& parentClique)
+        : prunedDiscreteFactor(prunedDiscreteFactor) {}
+
+    /**
+     * @brief A function used during tree traversal that operates on each node
+     * before visiting the node's children.
+     *
+     * @param node The current node being visited.
+     * @param parentData The data from the parent node.
+     * @return HybridPrunerData which is passed to the children.
+     */
+    static HybridPrunerData AssignmentPreOrderVisitor(
+        const HybridBayesTree::sharedNode& clique,
+        HybridPrunerData& parentData) {
+      // Get the conditional
+      HybridConditional::shared_ptr conditional = clique->conditional();
+
+      // If conditional is hybrid, we prune it.
+      if (conditional->isHybrid()) {
+        auto gaussianMixture = conditional->asMixture();
+
+        // Check if the number of discrete keys match,
+        // else we get an assignment error.
+        // TODO(Varun) Update prune method to handle assignment subset?
+        if (gaussianMixture->discreteKeys() ==
+            parentData.prunedDiscreteFactor.discreteKeys()) {
+          gaussianMixture->prune(parentData.prunedDiscreteFactor);
+        }
+      }
+      return parentData;
+    }
+  };
+
+  HybridPrunerData rootData(prunedDiscreteFactor, 0);
+  {
+    treeTraversal::no_op visitorPost;
+    // Limits OpenMP threads since we're mixing TBB and OpenMP
+    TbbOpenMPMixedScope threadLimiter;
+    treeTraversal::DepthFirstForestParallel(
+        *this, rootData, HybridPrunerData::AssignmentPreOrderVisitor,
+        visitorPost);
+  }
+}
+
 }  // namespace gtsam
diff --git a/gtsam/hybrid/HybridBayesTree.h b/gtsam/hybrid/HybridBayesTree.h
index 3fa344d4d..d443e33c4 100644
--- a/gtsam/hybrid/HybridBayesTree.h
+++ b/gtsam/hybrid/HybridBayesTree.h
@@ -88,6 +88,13 @@ class GTSAM_EXPORT HybridBayesTree : public BayesTree<HybridBayesTreeClique> {
    */
   VectorValues optimize(const DiscreteValues& assignment) const;
 
+  /**
+   * @brief Prune the underlying Bayes tree.
+   *
+   * @param maxNumberLeaves The max number of leaf nodes to keep.
+   */
+  void prune(const size_t maxNumberLeaves);
+
   /// @}
 
  private:
diff --git a/gtsam/hybrid/HybridGaussianISAM.cpp b/gtsam/hybrid/HybridGaussianISAM.cpp
index bf2f60da6..0a9d0b0de 100644
--- a/gtsam/hybrid/HybridGaussianISAM.cpp
+++ b/gtsam/hybrid/HybridGaussianISAM.cpp
@@ -106,76 +106,4 @@ void HybridGaussianISAM::update(const HybridGaussianFactorGraph& newFactors,
   this->updateInternal(newFactors, &orphans, ordering, function);
 }
 
-/* ************************************************************************* */
-/**
- * @brief Check if `b` is a subset of `a`.
- * Non-const since they need to be sorted.
- *
- * @param a KeyVector
- * @param b KeyVector
- * @return True if the keys of b is a subset of a, else false.
- */
-bool IsSubset(KeyVector a, KeyVector b) {
-  std::sort(a.begin(), a.end());
-  std::sort(b.begin(), b.end());
-  return std::includes(a.begin(), a.end(), b.begin(), b.end());
-}
-
-/* ************************************************************************* */
-void HybridGaussianISAM::prune(const size_t maxNrLeaves) {
-  auto decisionTree = boost::dynamic_pointer_cast<DecisionTreeFactor>(
-      this->roots_.at(0)->conditional()->inner());
-
-  DecisionTreeFactor prunedDiscreteFactor = decisionTree->prune(maxNrLeaves);
-  decisionTree->root_ = prunedDiscreteFactor.root_;
-
-  /// Helper struct for pruning the hybrid bayes tree.
-  struct HybridPrunerData {
-    /// The discrete decision tree after pruning.
-    DecisionTreeFactor prunedDiscreteFactor;
-    HybridPrunerData(const DecisionTreeFactor& prunedDiscreteFactor,
-                     const HybridBayesTree::sharedNode& parentClique)
-        : prunedDiscreteFactor(prunedDiscreteFactor) {}
-
-    /**
-     * @brief A function used during tree traversal that operates on each node
-     * before visiting the node's children.
-     *
-     * @param node The current node being visited.
-     * @param parentData The data from the parent node.
-     * @return HybridPrunerData which is passed to the children.
-     */
-    static HybridPrunerData AssignmentPreOrderVisitor(
-        const HybridBayesTree::sharedNode& clique,
-        HybridPrunerData& parentData) {
-      // Get the conditional
-      HybridConditional::shared_ptr conditional = clique->conditional();
-
-      // If conditional is hybrid, we prune it.
-      if (conditional->isHybrid()) {
-        auto gaussianMixture = conditional->asMixture();
-
-        // Check if the number of discrete keys match,
-        // else we get an assignment error.
-        // TODO(Varun) Update prune method to handle assignment subset?
-        if (gaussianMixture->discreteKeys() ==
-            parentData.prunedDiscreteFactor.discreteKeys()) {
-          gaussianMixture->prune(parentData.prunedDiscreteFactor);
-        }
-      }
-      return parentData;
-    }
-  };
-
-  HybridPrunerData rootData(prunedDiscreteFactor, 0);
-  {
-    treeTraversal::no_op visitorPost;
-    // Limits OpenMP threads since we're mixing TBB and OpenMP
-    TbbOpenMPMixedScope threadLimiter;
-    treeTraversal::DepthFirstForestParallel(
-        *this, rootData, HybridPrunerData::AssignmentPreOrderVisitor,
-        visitorPost);
-  }
-}
-
 }  // namespace gtsam