The satisfactory ending to the incident in which a 22-year-old autistic man crossed into the mainland illegally, does not lessen concerns about security lapses at the border crossings. This time, fortunately, an alert immigration official on the mainland side spotted the man at the Huanggang control point. He had an identity bracelet round his neck, so it would have been easy enough to identify him even if he had managed to get to Dongguan. This time, too, he was recognised as mentally retarded and was dealt with in a proper manner. New police procedures meant that the Lok Ma Chau control point had been notified of a missing person, and so - despite a day in which he was apparently wandering around somewhere in Hong Kong - the man was returned to his home in Ma On Shan, none the worse for his adventure. It could have been a very different story. Yu Man-hon's parents are still searching for their lost 16-year-old son months after he managed to dodge the immigration desks and was passed backwards and forwards between the two authorities before being abandoned in Shenzhen. This time there is doubt as to whether the man passed through either checkpoint. There is no record of his having departed Hong Kong, but it is puzzling as to how he got so far. After the inquiry into the Man-hon case, in which immigration officers were criticised for lacking common sense, sensitivity and alertness, the department undertook to strengthen training methods and increase supervision. If a new investigation reveals more shortcomings in the system, they must be remedied immediately. This case may not be another lapse of security, but if it is, the question arises as to how many others are able to dodge the control points. Staff shortages and vastly increased cross-border traffic contributed to the first tragedy, and clearly minor slip-ups are inevitable when too few officers are processing too many travellers. With an average daily throughput at Lowu of 230,000, improvements have to be introduced before the system reaches breaking point; properly staffed, the 210 counters could cope with nearly twice that number, and once the smartcard problems are solved, crossing from one side to another will take a matter of minutes.