TAIPEI, Taiwan — Liu Hui-fen spent seven days completing a puzzle with a payoff — by far the most difficult she's ever attempted as the Taiwan Justice Ministry official in charge of helping citizens piece together currency that has been mangled.

With an aide, Liu cobbled together thousands of tiny paper money pieces worth 200,000 New Taiwan dollars ($6,600) in total and returned them to their owner Thursday.

The man, who only gave his surname, Lin, said he accidentally dumped a plastic bag containing 200 $1,000 Taiwan bills into an industrial scrap machine last month — and each were torn into some 20 pieces. He later went to the Justice Ministry's Investigation Bureau where Liu works to ask for help.

Stymied at first by the unwieldy pile of scraps in front of her, Liu soon found a way to attack the problem. She located the Chinese character "guo," or country, on each bill, and then worked outwards.

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When the job was finally done she said it was the most difficult she'd ever accomplished, but said she also had a lot of fun helping Lin out. Liu usually investigates handwriting samples, but has a special brief to work on cases dealing with wrecked money — handling 247 of them in the past five years.

"I was so happy whenever I was able to put a piece into its right place," she said.

Under Taiwanese law, people can claim replacement bills from the central bank as long as at least 75 percent of the original is pieced together.

A chastened Lin expressed his sincere gratitude for Liu's perseverance.

"I'm sorry the job brought her so much trouble," he said.