diff --git a/src/registrar/admin.py b/src/registrar/admin.py
index 91bf58512..af2cb3104 100644
--- a/src/registrar/admin.py
+++ b/src/registrar/admin.py
@@ -555,13 +555,10 @@ class DomainApplicationAdmin(ListHeaderAdmin):
         parameter_name = "investigator"
 
         def lookups(self, request, model_admin):
-            """Lookup reimplementation, gets users by the MANAGER role.
+            """Lookup reimplementation, gets users of is_staff.
             Returns a list of tuples consisting of (user.id, user)
             """
-            valid_user_ids = UserDomainRole.objects.filter(role=UserDomainRole.Roles.MANAGER).values_list(
-                "user__id", flat=True
-            )
-            privileged_users = User.objects.filter(id__in=valid_user_ids)
+            privileged_users = User.objects.filter(is_staff=True)
             return [(user.id, user) for user in privileged_users]
 
         def queryset(self, request, queryset):
@@ -663,6 +660,7 @@ class DomainApplicationAdmin(ListHeaderAdmin):
         return super().formfield_for_manytomany(db_field, request, **kwargs)
 
     def get_queryset(self, request):
+        """Queryset reimplementation to order the table alphabetically"""
         query_set = super().get_queryset(request)
         return query_set.order_by("requested_domain__name")
 
diff --git a/src/registrar/tests/test_admin.py b/src/registrar/tests/test_admin.py
index a9181f97e..a3969d386 100644
--- a/src/registrar/tests/test_admin.py
+++ b/src/registrar/tests/test_admin.py
@@ -848,6 +848,7 @@ class TestDomainApplicationAdmin(MockEppLib):
         request = self.factory.get("/")
         request.user = self.superuser
 
+        # Grab the current list of table filters
         readonly_fields = self.admin.get_list_filter(request)
         expected_fields = ("status", "organization_type", DomainApplicationAdmin.InvestigatorFilter)
 
@@ -859,13 +860,37 @@ class TestDomainApplicationAdmin(MockEppLib):
         self.client.login(username="staffuser", password=p)
         response = self.client.get(
             "/admin/registrar/domainapplication/",
-            {},
-            follow=True,
         )
+        
+        # Create a mock DomainApplication object, with a fake investigator
+        application: DomainApplication = generic_domain_object("application", "SomeGuy")
 
+        # Add the role manager to the investigator
+        UserDomainRole.objects.get_or_create(
+            user=application.investigator,
+            role=UserDomainRole.Roles.MANAGER,
+            domain=Domain.objects.create(name="SomeGuy.gov")
+        )
+        
+        # First, make sure that there is still an investigator field to begin with
         expected_sort_column = "sortable column-investigator"
         self.assertContains(response, expected_sort_column, count=1)
 
+        # Then, test if the filter actually exists
+        self.assertIn("filters", response.context)
+        # Assert the content of filters and search_query
+        filters = response.context["filters"]
+        self.assertEqual(
+            filters,
+            [
+                {"parameter_name": "status", "parameter_value": "started"},
+                {
+                    "parameter_name": "investigator",
+                    "parameter_value": "test",
+                },
+            ],
+        )
+
     def test_investigator_filter(self):
         """Tests the custom investigator filter"""
         # Creates multiple domain applications