Не убирается экранирование в JSON ответе

function getRefByUserID($apiMethodParams)
    {
        $retJSON = $this->createDefaultJson();
        if (isset($apiMethodParams))
        {
            $refUserID = $apiMethodParams->UserID;
            $query = "Select * From refs where UserID = " . $refUserID;
            $result = mysqli_query($this->mySQLWorker->connectLink, $query);

            if (mysqli_num_rows($result) != 0)
            {
                while($row=$result->fetch_row())
                {
                    $ref = new Reference($row[0], $row[1], $row[2], $row[3], $row[4], $row[5], $row[6]);
                    $retJSON->Result = json_encode($ref, JSON_UNESCAPED_SLASHES);
                }
            }
            else{
                $retJSON->Error = APIConstants::$ERROR_CAN_NOT_ROW;
            }
        }
        else
        {
            $retJSON->error = APIConstants::$ERROR_PARAMS;
        }
        return $retJSON;
    }

Результат:

{"response":{"Result":"{\"ID\":\"3\",\"UserID\":\"42\",\"Type\":\"0\",\"FullName\":\"sdfdvcxvxcv\",\"GroupNumber\":\"420\",\"Count\":\"2\",\"Date\":\"2012-12-19\"}"}}

Как убрать лишние слэш?