private function deleteTombstone($path) {
    $response = $this->fedora->getResourceHeaders($path);
    $return = NULL;
    if ($response->getStatusCode() == 410) {
      $return = FALSE;
      $link_headers = Psr7\parse_header($response->getHeader('Link'));
      if ($link_headers) {
        $tombstones = array_filter($link_headers, function ($o) {
          return (isset($o['rel']) && $o['rel'] == 'hasTombstone');
        });
        foreach ($tombstones as $tombstone) {
          // Trim <> from URL.
          $url = rtrim(ltrim($tombstone[0], '<'), '>');
          $response = $this->fedora->deleteResource($url);
          if ($response->getStatusCode() == 204) {
            $return = TRUE;
          }
        }
      }
    }
    return $return;
  }