The Immigration Department is considering disciplinary action against officers who allowed an 82-year-old woman with senile dementia to slip through the Lowu border crossing without travel documents.
An internal investigation found that Ngan Yau-lan was stopped at the checkpoint on the afternoon of August 21 but went missing before being questioned or processed through immigration. She was found in Shenzhen the following day and sent back home.
The department found officers involved did not deal with the matter properly, and disciplinary action could be taken.
The incident coincides with the second anniversary of the disappearance of autistic Hong Kong boy Yu Man-hon, 15, who was mistakenly sent across the border by SAR immigration officials and is still missing.
Mrs Ngan's family has criticised the efficiency of immigration officers on both sides of the border, while legislators say unauthorised border crossings caused by overcrowding will continue if the Immigration Department fails to improve security measures.
But the department concluded that existing measures to prevent people slipping through the border were effective in general and stressed the 'isolated incident' would not affect the checkpoints' smooth operation.
A spokesman said last night the department had already reminded all officers to be alert to people wandering around checkpoints. He said the department would spend $134.8 million in the next three years to improve facilities at Lowu.
One main project would be to install 114 closed-circuit televisions to monitor the flow of people by next April, which could prevent further unauthorised crossings.
Nearly 150 million people crossed the border checkpoints last year, with an average of more than 400,000 a day.
Mrs Ngan's family was not available to comment on the investigation findings last night.