string sql = String.Format("select Peer_guid from State where file_md5 = '{0}'", md5);
        List<string> guids = new List<string>();

        try
        {
            using (SQLiteConnection c = new SQLiteConnection(ConnectionString))
            {
                c.Open();
                using (SQLiteCommand cmd = new SQLiteCommand(sql, c))
                {
                    SQLiteDataReader reader = cmd.ExecuteReader();
                    while (reader.Read())
                    {
                        string guid = (string)reader["Peer_guid"];
                        guids.Add(guid);
                    }
                    reader.Close();
                    reader.Dispose();
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error ({0}): {1}", ex.Message, ex.StackTrace);
            logFile.WriteErrorLog(ex.ToString());
            return null;
        }

        return guids;