$params = array(array('group', 'IN', array($groupID => 1), 0, 0));
$returnProperties = array('contact_id');
list($contacts, $_) = CRM_Contact_BAO_Query::apiQuery($params, $returnProperties, NULL, NULL, 0, 0, $useCache);
$params = array(array('group', 'IN', array($groupID => 1), 0, 0));
$returnProperties = array('contact_id');
list($contacts, $_) = CRM_Contact_BAO_Query::apiQuery($params, $returnProperties, NULL, NULL, 0, 0, $useCache);