diff --git a/_delete_person.php b/_delete_person.php
index 2b824f5..fd29201 100644
--- a/_delete_person.php
+++ b/_delete_person.php
@@ -2,15 +2,50 @@
 require_once 'db/config.php';
 session_start();
 
+header('Content-Type: application/json');
+
+if ($_SERVER['REQUEST_METHOD'] === 'POST') {
+    if (isset($_POST['person_id'])) {
+        $id = $_POST['person_id'];
+
+        try {
+            $pdo = db();
+            $stmt = $pdo->prepare("DELETE FROM people WHERE id = ?");
+            $stmt->execute([$id]);
+
+            if ($stmt->rowCount() > 0) {
+                echo json_encode(['success' => true, 'message' => 'Osoba usunięta pomyślnie.']);
+            } else {
+                http_response_code(404);
+                echo json_encode(['success' => false, 'error' => 'Nie znaleziono osoby.']);
+            }
+        } catch (PDOException $e) {
+            http_response_code(500);
+            // Log the real error to a secure log file
+            error_log("Database error on person delete: " . $e->getMessage());
+            // Send a generic error message to the client
+            echo json_encode(['success' => false, 'error' => 'Błąd serwera podczas usuwania osoby.']);
+        }
+        exit;
+    }
+    http_response_code(400);
+    echo json_encode(['success' => false, 'error' => 'Brak ID osoby.']);
+    exit;
+}
+
+// Keep GET for backwards compatibility or simple cases, but it redirects.
 if (isset($_GET['id'])) {
     $id = $_GET['id'];
-    
+
     $pdo = db();
     $stmt = $pdo->prepare("DELETE FROM people WHERE id = ?");
     $stmt->execute([$id]);
-    
+
     $_SESSION['success_message'] = 'Osoba usunięta pomyślnie.';
     header('Location: persons.php');
     exit;
 }
+
+http_response_code(405);
+echo json_encode(['success' => false, 'error' => 'Nieprawidłowa metoda żądania.']);
 ?>
\ No newline at end of file
diff --git a/index.php b/index.php
index c4db48c..2daba49 100644
--- a/index.php
+++ b/index.php
@@ -227,11 +227,11 @@ $status_colors = [
                         <div class="col-md-4">
                             <div class="mb-3">
                                 <label for="editFirstName" class="form-label">Imię</label>
-                                <input type="text" class="form-control" id="editFirstName" name="firstName" required>
+                                <input type="text" class="form-control" id="editFirstName" name="first_name" required>
                             </div>
                             <div class="mb-3">
                                 <label for="editLastName" class="form-label">Nazwisko</label>
-                                <input type="text" class="form-control" id="editLastName" name="lastName" required>
+                                <input type="text" class="form-control" id="editLastName" name="last_name" required>
                             </div>
                              <div class="mb-3">
                                 <label for="editPhone" class="form-label">Numer telefonu</label>
@@ -274,7 +274,7 @@ $status_colors = [
                             </div>
                              <div class="mb-3">
                                 <label for="editCompanyName" class="form-label">Nazwa firmy</label>
-                                <input type="text" class="form-control" id="editCompanyName" name="companyName">
+                                <input type="text" class="form-control" id="editCompanyName" name="company_name">
                             </div>
                         </div>
                         <div class="col-md-4">
@@ -355,11 +355,11 @@ $status_colors = [
                         <div class="col-md-4">
                             <div class="mb-3">
                                 <label for="createFirstName" class="form-label">First Name <span class="text-danger">*</span></label>
-                                <input type="text" class="form-control" id="createFirstName" name="firstName" required>
+                                <input type="text" class="form-control" id="createFirstName" name="first_name" required>
                             </div>
                             <div class="mb-3">
                                 <label for="createLastName" class="form-label">Last Name <span class="text-danger">*</span></label>
-                                <input type="text" class="form-control" id="createLastName" name="lastName" required>
+                                <input type="text" class="form-control" id="createLastName" name="last_name" required>
                             </div>
                              <div class="mb-3">
                                 <label for="createPhone" class="form-label">Phone Number</label>
@@ -403,7 +403,7 @@ $status_colors = [
                             </div>
                              <div class="mb-3">
                                 <label for="createCompanyName" class="form-label">Company Name</label>
-                                <input type="text" class="form-control" id="createCompanyName" name="companyName">
+                                <input type="text" class="form-control" id="createCompanyName" name="company_name">
                             </div>
                         </div>
                         <div class="col-md-4">
@@ -512,7 +512,7 @@ document.addEventListener('DOMContentLoaded', function () {
         var modalBody = instanceModal.querySelector('.modal-body');
 
         // Load content via AJAX
-        fetch(`_get_instance_details.php?personId=${personId}&processId=${processId}`)
+        fetch(`_get_instance_details.php?person_id=${personId}&process_id=${processId}`)
             .then(response => response.text())
             .then(html => {
                 modalBody.innerHTML = html;
@@ -565,10 +565,10 @@ document.addEventListener('DOMContentLoaded', function () {
                 .then(response => response.json())
                 .then(data => {
                     document.getElementById('editPersonId').value = data.person.id;
-                    document.getElementById('editFirstName').value = data.person.firstName;
-                    document.getElementById('editLastName').value = data.person.lastName;
+                    document.getElementById('editFirstName').value = data.person.first_name;
+                    document.getElementById('editLastName').value = data.person.last_name;
                     document.getElementById('editEmail').value = data.person.email;
-                    document.getElementById('editCompanyName').value = data.person.companyName;
+                    document.getElementById('editCompanyName').value = data.person.company_name;
                     document.getElementById('editPhone').value = data.person.phone;
                     document.getElementById('editRole').value = data.person.role;
                     document.getElementById('editBniGroup').value = data.person.bni_group_id || '';