diff --git a/backend/resolution_proof_service.py b/backend/resolution_proof_service.py
index 1bbd1db9..199d9920 100644
--- a/backend/resolution_proof_service.py
+++ b/backend/resolution_proof_service.py
@@ -464,13 +464,13 @@ def verify_evidence(grievance_id: int, db: Session) -> Dict[str, Any]:
         Returns:
             Verification result dictionary
         """
-        # Optimized: Use .count() and .first() to avoid loading all historical evidence
-        # records into memory, reducing O(N) database transfer and memory overhead.
-        evidence_count = db.query(ResolutionEvidence).filter(
+        # Optimized: Evaluate .first() prior to .count() to enable early exit
+        # when no evidence exists, reducing database round-trips.
+        evidence = db.query(ResolutionEvidence).filter(
             ResolutionEvidence.grievance_id == grievance_id
-        ).count()
+        ).order_by(ResolutionEvidence.id.desc()).first()
 
-        if evidence_count == 0:
+        if not evidence:
             return {
                 "grievance_id": grievance_id,
                 "is_verified": False,
@@ -483,10 +483,10 @@ def verify_evidence(grievance_id: int, db: Session) -> Dict[str, Any]:
                 "message": "No resolution evidence found for this grievance"
             }
 
-        # Use the most recent evidence
-        evidence = db.query(ResolutionEvidence).filter(
+        # Total count is still needed for the response
+        evidence_count = db.query(ResolutionEvidence).filter(
             ResolutionEvidence.grievance_id == grievance_id
-        ).order_by(ResolutionEvidence.id.desc()).first()
+        ).count()
 
         # Re-verify the server signature
         bundle_str = json.dumps(evidence.metadata_bundle, sort_keys=True)
diff --git a/backend/routers/voice.py b/backend/routers/voice.py
index 5ec6e385..f2079a20 100644
--- a/backend/routers/voice.py
+++ b/backend/routers/voice.py
@@ -11,10 +11,12 @@
 import logging
 import os
 import uuid
+import hashlib
 from datetime import datetime, timezone
 
 from backend.database import get_db
 from backend.models import Issue
+from backend.cache import blockchain_last_hash_cache
 from backend.schemas import (
     VoiceTranscriptionResponse,
     TextTranslationRequest,
@@ -254,6 +256,21 @@ async def submit_voice_issue(
         # Store relative path for portability
         relative_audio_path = os.path.join("data", "audio_recordings", audio_filename)
         
+        # Blockchain feature: calculate integrity hash for the report
+        # Performance Boost: Use thread-safe cache to eliminate DB query for last hash
+        prev_hash = blockchain_last_hash_cache.get("last_hash")
+        if prev_hash is None:
+            # Cache miss: Fetch only the last hash from DB
+            prev_issue = await run_in_threadpool(
+                lambda: db.query(Issue.integrity_hash).order_by(Issue.id.desc()).first()
+            )
+            prev_hash = prev_issue[0] if prev_issue and prev_issue[0] else ""
+            blockchain_last_hash_cache.set(data=prev_hash, key="last_hash")
+
+        # Simple but effective SHA-256 chaining
+        hash_content = f"{final_description}|{issue_category.value}|{prev_hash}"
+        integrity_hash = hashlib.sha256(hash_content.encode()).hexdigest()
+
         # Create issue in database
         reference_id = generate_reference_id()
         
@@ -273,12 +290,17 @@ async def submit_voice_issue(
             original_text=original_text,
             transcription_confidence=voice_result.get('confidence', 0.0),
             manual_correction_applied=manual_correction_applied,
-            audio_file_path=relative_audio_path  # Store relative path
+            audio_file_path=relative_audio_path,  # Store relative path
+            integrity_hash=integrity_hash,
+            previous_integrity_hash=prev_hash
         )
         
         db.add(new_issue)
         db.commit()
         db.refresh(new_issue)
+
+        # Update cache for next report AFTER successful DB commit
+        blockchain_last_hash_cache.set(data=integrity_hash, key="last_hash")
         
         logger.info(f"Voice issue created: ID={new_issue.id}, Language={voice_result.get('source_language')}, Confidence={voice_result.get('confidence')}")