private function _authenticate($credentials)
    {
        try {
            $response = $this->getService('com:people.authentication.response');
            dispatch_plugin('authentication.onAuthenticate', array(
                                'credentials' => $credentials,
                                'response' => $response
                            ));

            if ($response->status === ComPeopleAuthentication::STATUS_SUCCESS) {
                return true;
            }

        } catch (RuntimeException $e) {
            //only throws exception if we are using JSON format
            //otherwise let the current app handle it
            if (AnRequest::format() == 'json') {
                throw $e;
            }
        }

        return false;
    }