diff --git a/app/(protected)/hse/incidents/[id]/page.tsx b/app/(protected)/hse/incidents/[id]/page.tsx
index d5331b3..7edff7b 100644
--- a/app/(protected)/hse/incidents/[id]/page.tsx
+++ b/app/(protected)/hse/incidents/[id]/page.tsx
@@ -6,6 +6,7 @@ import { IncidentDetail, type Incident } from '@/components/incidents/incident-d
 import { IncidentHeader } from '@/components/incidents/incident-header'
 import { SimilarIncidentsPanel } from '@/components/incidents/similar-incidents-panel'
 import { ClosurePanel } from '@/components/incidents/closure-panel'
+import { InvestigationPanel } from '@/components/incidents/investigation-panel'
 
 interface Props {
   params: Promise<{ id: string }>
@@ -35,6 +36,17 @@ export default async function HseIncidentDetailPage({ params }: Props) {
 
   const status = (incident as { status: string }).status
 
+  const { data: investigation } = await supabase
+    .from('investigations')
+    .select(`
+      id, method, five_why_steps, fishbone_categories,
+      findings_text, root_cause_summary, alcohol_test_result,
+      witness_statement_refs, completed_at,
+      investigator:users!investigator_id (name, email)
+    `)
+    .eq('incident_id', id)
+    .maybeSingle()
+
   const needsJkkp = Boolean(
     (incident as { is_fatality?: boolean }).is_fatality ||
     (incident as { is_serious_bodily_injury?: boolean }).is_serious_bodily_injury ||
@@ -56,6 +68,10 @@ export default async function HseIncidentDetailPage({ params }: Props) {
       <main className="max-w-3xl mx-auto px-4 py-6">
         <IncidentDetail incident={incident as unknown as Incident} />
 
+        {investigation && (
+          <InvestigationPanel investigation={investigation as never} />
+        )}
+
         {needsJkkp && (
           <div className="mt-4 flex gap-3 flex-wrap">
             <a
diff --git a/components/incidents/investigation-panel.tsx b/components/incidents/investigation-panel.tsx
new file mode 100644
index 0000000..de0ee58
--- /dev/null
+++ b/components/incidents/investigation-panel.tsx
@@ -0,0 +1,130 @@
+type FiveWhyStep = { why: string; answer: string }
+
+interface Investigation {
+  id: string
+  method: 'five_why' | 'fishbone' | 'other'
+  five_why_steps: FiveWhyStep[] | null
+  fishbone_categories: Record<string, string> | null
+  findings_text: string | null
+  root_cause_summary: string | null
+  alcohol_test_result: string | null
+  witness_statement_refs: string[]
+  completed_at: string | null
+  investigator: { name: string | null; email: string } | null
+}
+
+interface Props {
+  investigation: Investigation
+}
+
+const METHOD_LABELS = {
+  five_why: '5-Why Analysis',
+  fishbone: 'Fishbone (Ishikawa)',
+  other: 'Other Method',
+}
+
+export function InvestigationPanel({ investigation: inv }: Props) {
+  const investigatorName = inv.investigator?.name ?? inv.investigator?.email ?? 'Unknown'
+
+  return (
+    <div className="mt-6 bg-white rounded-xl shadow-sm border border-gray-200 overflow-hidden">
+      <div className="flex items-center justify-between px-5 py-4 border-b border-gray-100">
+        <h2 className="text-sm font-semibold text-gray-900">Investigation</h2>
+        <div className="flex items-center gap-2">
+          <span className="text-xs text-gray-500">{METHOD_LABELS[inv.method] ?? inv.method}</span>
+          <span className={`text-xs font-medium px-2 py-0.5 rounded-full ${
+            inv.completed_at
+              ? 'bg-green-100 text-green-700'
+              : 'bg-yellow-100 text-yellow-700'
+          }`}>
+            {inv.completed_at ? 'Completed' : 'In Progress'}
+          </span>
+        </div>
+      </div>
+
+      <div className="px-5 py-4 space-y-5">
+        <p className="text-xs text-gray-500">
+          Investigator: <span className="font-medium text-gray-700">{investigatorName}</span>
+          {inv.completed_at && (
+            <span className="ml-2">
+              · Completed {new Date(inv.completed_at).toLocaleDateString('en-MY', { day: 'numeric', month: 'short', year: 'numeric' })}
+            </span>
+          )}
+        </p>
+
+        {/* 5-Why steps */}
+        {inv.method === 'five_why' && inv.five_why_steps && inv.five_why_steps.length > 0 && (
+          <div>
+            <h3 className="text-xs font-semibold text-gray-500 uppercase tracking-wide mb-3">5-Why Steps</h3>
+            <ol className="space-y-3">
+              {inv.five_why_steps.map((step, i) => (
+                <li key={i} className="flex gap-3">
+                  <span className="flex-shrink-0 w-6 h-6 rounded-full bg-blue-100 text-blue-700 text-xs font-bold flex items-center justify-center">
+                    {i + 1}
+                  </span>
+                  <div className="flex-1 min-w-0">
+                    <p className="text-xs font-medium text-gray-700">{step.why}</p>
+                    {step.answer && (
+                      <p className="text-sm text-gray-900 mt-0.5">{step.answer}</p>
+                    )}
+                  </div>
+                </li>
+              ))}
+            </ol>
+          </div>
+        )}
+
+        {/* Fishbone categories */}
+        {inv.method === 'fishbone' && inv.fishbone_categories && Object.keys(inv.fishbone_categories).length > 0 && (
+          <div>
+            <h3 className="text-xs font-semibold text-gray-500 uppercase tracking-wide mb-3">Fishbone Categories</h3>
+            <dl className="space-y-2">
+              {Object.entries(inv.fishbone_categories).map(([cat, val]) => (
+                <div key={cat}>
+                  <dt className="text-xs font-medium text-gray-500 capitalize">{cat}</dt>
+                  <dd className="text-sm text-gray-900">{val}</dd>
+                </div>
+              ))}
+            </dl>
+          </div>
+        )}
+
+        {/* Findings */}
+        {inv.findings_text && (
+          <div>
+            <h3 className="text-xs font-semibold text-gray-500 uppercase tracking-wide mb-1">Findings</h3>
+            <p className="text-sm text-gray-900 whitespace-pre-wrap">{inv.findings_text}</p>
+          </div>
+        )}
+
+        {/* Root cause */}
+        {inv.root_cause_summary && (
+          <div className="bg-red-50 border border-red-100 rounded-lg px-4 py-3">
+            <h3 className="text-xs font-semibold text-red-600 uppercase tracking-wide mb-1">Root Cause</h3>
+            <p className="text-sm text-gray-900 whitespace-pre-wrap">{inv.root_cause_summary}</p>
+          </div>
+        )}
+
+        {/* Alcohol test */}
+        {inv.alcohol_test_result && (
+          <div>
+            <h3 className="text-xs font-semibold text-gray-500 uppercase tracking-wide mb-1">Alcohol Test Result</h3>
+            <p className="text-sm text-gray-900">{inv.alcohol_test_result}</p>
+          </div>
+        )}
+
+        {/* Witness refs */}
+        {inv.witness_statement_refs && inv.witness_statement_refs.length > 0 && (
+          <div>
+            <h3 className="text-xs font-semibold text-gray-500 uppercase tracking-wide mb-1">Witness Statements</h3>
+            <ul className="list-disc list-inside space-y-1">
+              {inv.witness_statement_refs.map((ref, i) => (
+                <li key={i} className="text-sm text-gray-900">{ref}</li>
+              ))}
+            </ul>
+          </div>
+        )}
+      </div>
+    </div>
+  )
+}