Thanks to hard work by the Kowloon West Regional Missing Persons Unit (RMPU), Shanghaiese Ms Wang Lin was reunited with her missing Hong Kong adoptive mother Ms Tong Mei-ying after a separation lasting almost half a century.

The pair were overjoyed with the reunion and told OffBeat they would never forget the police officers who worked so hard to mend their broken link. Earlier, Ms Wang presented pennants to the Kowloon West RMPU and the Wan Chai Police Station in appreciation of their good work.

"I missed her very much. I didn't have her address and could think of nowhere to go to look for her. The world is so big," said Ms Tong, now 73. "Hui Sir, thank you very much! I really do thank you."

"I was just doing my job," replied Sergeant Mr Hui Yuk-choi, who visited Ms Tong's home again after the reunion. "I was lucky. I am so happy to have found Ms Wang's relative alive and well in Hong Kong."

In the early 1950s, Ms Tong was still a young lady. On a rainy day, she saw a months-old baby girl dumped beside some rubbish near the Western waterfront. She said: "I was afraid she was hungry and that no one would look after her. It would have been cruel to leave her there. So, I adopted the girl."

For some reason, the orphan - Ms Wang - was taken to Shanghai and they lost contact a few years later. Ms Wang, now a mother herself, exhausted every avenue in her search for her mother, hoping that she might still be living in the town. She visited the last-known address of her mother twice. She placed newspaper advertisements. She sought help from the Red Cross. But all her efforts were in vain.

When Ms Wang visited Hong Kong last June, she made a written request to Wan Chai Police Station, seeking Police help in locating her mother. The case was later handed over to the Kowloon West RMPU.

Soon after Mr Hui took over the case, he searched through the records of the Police and the Social Welfare Department to get hints of the whereabouts of Ms Wang's mother. He went through many files and short-listed people with similar names, ages and characteristics. After checking all the details, he decided to visit Ms Tong's home to ensure that he had made an exact match.

He said: "When she took out the wallet to show me the identity card, I spotted a photo taken decades ago. Bingo! Her face in the photo looked the same as the face in a photo provided by Ms Wang. I knew that she was the one for whom I was looking.

"After further enquiries, I asked her to take a closer look at the photo given to me by Ms Wang, and she immediately pointed at the photo and said, 'This person is me'. Then she started to recall her memories."

"When I finally met her at the train station, I recognised her straightaway. The outline of her face was more or less the same," said Ms Tong with a smile.

In a letter to the Commissioner of Police, Ms Wang highly praised the efficiency of the Force as well as the conscientious attitude of the Police officers.

She wrote: "Now, I am over 50 years old. I thought that, if, at her age, my mother was still alive, then she would probably be in need of help. And I often felt uncomfortable at being unable to show her the filial piety to which she was due.

"Though Ms Tong is only my adoptive mother, she deserves more respect than my natural mother. I am lucky to have a mother like her. I also can't help express my heartfelt thanks to those who helped me to find her."

Having worked in the RMPU for more than three years, Mr Hui said it was often difficult to find a missing person because of a lack of sufficient information. This was not the first time that Mr Hui successfully located the whereabouts of missing persons for people living on the Mainland. But not all cases had such a happy ending as this one.

"For example, in 2001, an elderly man living on the Mainland sought our help in finding his Hong Kong son after he suddenly lost contact with him. We started a man search. But in that case, we found that his son had passed away," he said.

The Kowloon West RMPU handles more than 1,200 missing person cases each year and officers have to work under great pressure to find them. Without exception, Mr Hui has to race against time to locate "high-risk persons" such as toddlers and adults with a suicidal tendency.

"Everyone in the RMPU works wholeheartedly on each case. We work as a team. For example, when we handle a 'high risk' case, one of my colleagues will check with hospitals and the others will talk to officers in other Police districts. We have established a good and close working relationship," he added.

Mother and daughter reunited after decades apart