diff --git a/src/apps/support/README.md b/src/apps/support/README.md
index eaad0a17d..ead5236ab 100644
--- a/src/apps/support/README.md
+++ b/src/apps/support/README.md
@@ -3,7 +3,8 @@
 The Support subapp lets authenticated Topcoder members open requests, follow
 their status, and reply to the Topcoder Support Team. Users with the exact
 `Topcoder Support Team` role can see all tickets, assign themselves, search
-closed tickets, reply to tickets assigned to them, and close resolved requests.
+closed tickets, and reply to or close resolved requests assigned to them.
+Closed ticket details identify the Support Team user who closed the request.
 
 ## Routes
 
diff --git a/src/apps/support/src/lib/models/support.models.ts b/src/apps/support/src/lib/models/support.models.ts
index 5c346295f..f0c94d64f 100644
--- a/src/apps/support/src/lib/models/support.models.ts
+++ b/src/apps/support/src/lib/models/support.models.ts
@@ -33,6 +33,7 @@ export interface SupportTicketSummary {
     status: SupportTicketStatus
     openedAt: string
     closedAt?: string
+    closedByUserId?: string
     updatedAt: string
     latestActivityAt: string
     responseCount: number
diff --git a/src/apps/support/src/pages/ticket-details/TicketDetailPage.spec.tsx b/src/apps/support/src/pages/ticket-details/TicketDetailPage.spec.tsx
index 66b321d20..9e69ac6a5 100644
--- a/src/apps/support/src/pages/ticket-details/TicketDetailPage.spec.tsx
+++ b/src/apps/support/src/pages/ticket-details/TicketDetailPage.spec.tsx
@@ -196,6 +196,49 @@ describe('TicketDetailPage reply access', () => {
             .toBeTruthy()
     })
 
+    it('identifies the support staff member who closed the ticket', () => {
+        mockUseSWR.mockReturnValue({
+            data: {
+                ...closedTicket,
+                assignees: [{
+                    assignedAt: '2026-08-07T00:30:00.000Z',
+                    handle: 'support-agent',
+                    userId: '99999',
+                }],
+                closedByUserId: '99999',
+            },
+            error: undefined,
+            isValidating: false,
+            mutate: mockMutate,
+        })
+
+        render(<TicketDetailPage />)
+
+        expect(screen.getByText((_content, element) => (
+            element?.tagName === 'P'
+            && element.textContent?.includes('Closed') === true
+            && element.textContent?.includes('by support-agent') === true
+        )))
+            .toBeTruthy()
+    })
+
+    it('falls back to the stored closer user ID when no assignee snapshot matches', () => {
+        mockUseSWR.mockReturnValue({
+            data: {
+                ...closedTicket,
+                closedByUserId: 'legacy-staff-1',
+            },
+            error: undefined,
+            isValidating: false,
+            mutate: mockMutate,
+        })
+
+        render(<TicketDetailPage />)
+
+        expect(screen.getByText('legacy-staff-1'))
+            .toBeTruthy()
+    })
+
     it('preserves freshly revalidated assignees when marking a ticket read completes', async () => {
         const markReadRequest = createDeferred<void>()
         mockedMarkRead.mockReturnValue(markReadRequest.promise)
@@ -242,7 +285,7 @@ describe('TicketDetailPage reply access', () => {
             .toBeUndefined()
     })
 
-    it('requires non-owner support staff to assign an open ticket before replying', () => {
+    it('requires non-owner support staff to assign an open ticket before replying or closing it', () => {
         mockProfile = {
             roles: ['Topcoder Support Team'],
             userId: 99999,
@@ -264,9 +307,13 @@ describe('TicketDetailPage reply access', () => {
             .toBeNull()
         expect(screen.getByText('Assign this ticket to yourself before replying.'))
             .toBeTruthy()
+        expect((screen.getByRole('button', {
+            name: 'Close support ticket',
+        }) as HTMLButtonElement).disabled)
+            .toBe(true)
     })
 
-    it('lets assigned support staff reply to an open ticket', () => {
+    it('lets assigned support staff reply to and close an open ticket', () => {
         mockProfile = {
             roles: ['Topcoder Support Team'],
             userId: 99999,
@@ -293,5 +340,9 @@ describe('TicketDetailPage reply access', () => {
             .toBeTruthy()
         expect(screen.queryByText('Assign this ticket to yourself before replying.'))
             .toBeNull()
+        expect((screen.getByRole('button', {
+            name: 'Close support ticket',
+        }) as HTMLButtonElement).disabled)
+            .toBe(false)
     })
 })
diff --git a/src/apps/support/src/pages/ticket-details/TicketDetailPage.tsx b/src/apps/support/src/pages/ticket-details/TicketDetailPage.tsx
index 4df066db3..8ac4bfeb5 100644
--- a/src/apps/support/src/pages/ticket-details/TicketDetailPage.tsx
+++ b/src/apps/support/src/pages/ticket-details/TicketDetailPage.tsx
@@ -106,6 +106,9 @@ export const TicketDetailPage: FC = () => {
         assignee => String(assignee.userId) === currentUserId,
     ))
     const closed = data.status === 'CLOSED'
+    const closedByAssignee = data.closedByUserId
+        ? data.assignees.find(assignee => String(assignee.userId) === String(data.closedByUserId))
+        : undefined
     const ticketOwner = Boolean(currentUserId && String(data.memberUserId) === currentUserId)
     const canReply = ticketOwner || (!closed && (!supportTeam || assignedToCurrentUser))
     const replyContext = `${data.id}-reply-${replyRevision}`
@@ -234,6 +237,21 @@ export const TicketDetailPage: FC = () => {
                             Closed
                             {' '}
                             {formatSupportDate(data.closedAt)}
+                            {data.closedByUserId && (
+                                <>
+                                    {' '}
+                                    by
+                                    {' '}
+                                    <span>
+                                        {closedByAssignee ? (
+                                            <MemberHandle
+                                                color={closedByAssignee.handleColor}
+                                                handle={closedByAssignee.handle}
+                                            />
+                                        ) : data.closedByUserId}
+                                    </span>
+                                </>
+                            )}
                         </p>
                     )}
                 </div>
@@ -247,6 +265,7 @@ export const TicketDetailPage: FC = () => {
                             size='md'
                         />
                         <Button
+                            disabled={updatingAssignment || !assignedToCurrentUser}
                             label='Close support ticket'
                             onClick={() => setConfirmClose(true)}
                             primary