Singapore's worst breach of private data was discovered on July 4, but the fact that data was stolen was unearthed only after tests were done on the IT system six days later, the Committee of Inquiry (COI) investigating the attack heard yesterday.

The tests were carried out by Mr Henry Arianto (photo), an employee of SingHealth's IT vendor, the Integrated Health Information Systems. He told the COI he was initially informed by a staff member that a query returned no data results. But after he ran some tests on July 10, he found, among other things, that the outpatient prescription details of 160,000 people, including those of Prime Minister Lee Hsien Loong, had been stolen. The COI also uncovered failings in organisational processes and staff judgment.

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