diff --git a/src/registrar/assets/js/get-gov-admin.js b/src/registrar/assets/js/get-gov-admin.js
index 594628b16..80d4d13bd 100644
--- a/src/registrar/assets/js/get-gov-admin.js
+++ b/src/registrar/assets/js/get-gov-admin.js
@@ -144,13 +144,13 @@ function openInNewTab(el, removeAttribute = false){
     let investigatorSelect = document.querySelector("#id_investigator");
     let assignSelfButton = document.querySelector("#investigator__assign_self");
     if (investigatorSelect && assignSelfButton) {
+        let selector = django.jQuery(investigatorSelect)
         assignSelfButton.addEventListener('click', function() {
             let currentUserId = this.getAttribute("data-user-id");
             let currentUserName = this.getAttribute("data-user-name");
-            if (currentUserId && currentUserName){
+            if (selector && currentUserId && currentUserName){
                 // Logic borrowed from here:
                 // https://select2.org/programmatic-control/add-select-clear-items#create-if-not-exists
-                let selector = django.jQuery(investigatorSelect)
                 // Set the value, creating a new option if necessary
                 if (selector.find(`option[value='${currentUserId}']`).length) {
                     selector.val(currentUserId).trigger("change");
@@ -159,11 +159,22 @@ function openInNewTab(el, removeAttribute = false){
                     let currentUser = new Option(currentUserName, currentUserId, true, true);
                     // Append it to the select
                     selector.append(currentUser).trigger("change");
-                } 
+                }
             }else {
                 console.error("Could not assign current user.")
             }
         });
+
+        selector.on('change', function() {
+            let selectedValue = this.value;
+            if (selectedValue === "" || selectedValue === null) {
+                // If no investigator is selected, show the 'Assign to Self' button
+                assignSelfButton.parentElement.style.display = 'flex';
+            } else {
+                // If an investigator is selected, hide the 'Assign to Self' button
+                assignSelfButton.parentElement.style.display = 'none';
+            }
+        });
     }
 })();
 /** An IIFE for pages in DjangoAdmin that use a clipboard button
diff --git a/src/registrar/templates/django/admin/includes/detail_table_fieldset.html b/src/registrar/templates/django/admin/includes/detail_table_fieldset.html
index 72340ff37..ed1c9285f 100644
--- a/src/registrar/templates/django/admin/includes/detail_table_fieldset.html
+++ b/src/registrar/templates/django/admin/includes/detail_table_fieldset.html
@@ -174,7 +174,7 @@ This is using a custom implementation fieldset.html (see admin/fieldset.html)
                 {% endif %}
             </span>
         </div>
-    {% elif field.field.name == "investigator" %}
+    {% elif field.field.name == "investigator" and not original_object.investigator %}
         <div class="flex-container">
             <label aria-label="Assign yourself as the investigator"></label>
             <button id="investigator__assign_self"