public static function delete_evidence($id) {
        $params = self::validate_parameters(self::delete_evidence_parameters(), array(
            'id' => $id
        ));

        $evidence = api::read_evidence($params['id']);
        $uc = api::get_user_competency_by_id($evidence->get('usercompetencyid'));
        self::validate_context($uc->get_context());

        return api::delete_evidence($evidence);
    }