diff -u b/includes/project_issue.json.inc b/includes/project_issue.json.inc
--- b/includes/project_issue.json.inc
+++ b/includes/project_issue.json.inc
@@ -51,19 +51,6 @@
     }
     $author->url = !empty($author->uid) ? url('user/' . $author->uid, $options) : NULL;
 
-    // Retrieve file attachments on the issue node.
-    // Does not contain attachments on comments.
-    // @see comment_upload_project_issue_json_alter()
-    $attachments = array();
-    foreach ($issue->files as $fid => $file) {
-      // Attachments are keyed by comment ID. We treat the original issue node
-      // as post 0, so as to have all issue attachments in one property that can
-      // be processed by API consumers.
-      $attachments[0]['contributorId'] = $author->uid;
-      $attachments[0]['commentId'] = 0;
-      $attachments[0]['urls'][$fid] = file_create_url($file->filepath);
-    }
-
     // Populate basic issue data.
     $return = array(
       // Increase minor version when adding information.
@@ -92,9 +79,29 @@
       'projectTitle' => $project->title,
       'projectUrl' => url('node/' . $project->nid, $options),
       'projectName' => $project->project['uri'],
-      'attachments' => $attachments,
+      'contributors' => array(),
+      'attachments' => array(),
+    );
+
+    // Add the issue author as contributor.
+    $return['contributors'][$author->uid] = array(
+      'id' => $author->uid,
+      'uid' => $author->uid,
+      'name' => $author->name,
+      'url' => $author->url,
     );
 
+    // Add file attachments on the issue node (not comments).
+    // @see comment_upload_project_issue_json_alter()
+    foreach ($issue->files as $fid => $file) {
+      // Attachments are keyed by comment ID. We treat the original issue node
+      // as post 0, so as to have all issue attachments in one property that can
+      // be processed by API consumers.
+      $return['attachments'][0]['contributorId'] = $author->uid;
+      $return['attachments'][0]['commentId'] = 0;
+      $return['attachments'][0]['urls'][$fid] = file_create_url($file->filepath);
+    }
+
     // Retrieve and populate comments and contributors (comment authors).
     $result = db_query("SELECT c.cid, c.pid, c.status, c.timestamp, c.thread, u.name, u.uid FROM {comments} c INNER JOIN {users} u ON c.uid = u.uid WHERE c.nid = %d AND c.status = %d ORDER BY c.cid ASC", $issue->nid, COMMENT_PUBLISHED);
     while ($row = db_fetch_object($result)) {
@@ -102,12 +109,12 @@
         'id' => $row->uid,
         'uid' => $row->uid,
         'name' => $row->name,
-        'url' => url('user/' . $row->uid, $options),
+        'url' => !empty($row->uid) ? url('user/' . $row->uid, $options) : NULL,
       );
       $return['comments'][$row->cid] = array(
         'id' => $row->cid,
         'contributorId' => $row->uid,
-        'url' => url('node/' . $issue->nid, array('absolute' => TRUE, 'fragment' => 'comment-' . $row->cid)),
+        'url' => url('node/' . $issue->nid, $options + array('fragment' => 'comment-' . $row->cid)),
         'created' => $row->timestamp,
         'status' => $row->status,
         'parentId' => $row->pid,