Gillian Rodgers' last overseas trip was four years. And this month, she will be going to Blenheim. She decided to bring out her trusty, old suitcase to have it cleaned up and aired. Never did she imagined that in one of its pockets was a packet of drugs, discovered four years later.

"I was clearing it out and I saw this packet of white stuff and I thought, 'wow what's that?' I thought it was something to keep the suitcase dry. It was like a plastic packet, about three inches by two inches, and it was solid, like a cushion," she told the New Zealand Herald.

Not knowing what the tightly-packed bag of white powder was, nor where it came from nor who was its' intended recipient, Ms Rodgers decided to take the stash to the Albany police station for examination.

When the local police called her up to inform her of their findings, she couldn't believe what she heard.

"I couldn't believe it when the policewoman rung me back and said it was [amphetamine]. She said it was $50,000 worth," the 74-year-old grandmum said. "I didn't for one minute expect it to be drugs even though we were joking about it that it might have been."

Ms Rodgers remembers very well that she last used the suitcase during a month-long cruise around Australia four years ago. She said she was with a friend before flying home to Auckland from Sydney.

She also remembered that she secured and padlocked every pocket on her bag. Except the one in which the drugs were found.

"I'm baffled. Of course I didn't see anybody put it in there. The only time I was not in my possession of my luggage was when it was on the carousel and when I put it on the X-ray machine," Ms Rodgers said.

The discovery has now placed in question the airports and their respective screening processes.

Nicky Elliott, Customs spokeswoman, said its difficult to trace where and when the drugs were placed in the suitcase.

"This could have happened anytime since she last used the suitcase," she said.

She did say however that passengers are only stopped at airports where there are alerts during routine screening procedures.

"We are confident this system works well and that the border is fully protected."

Inspector Shanan Gray, North Shore area commander, said it might take a hard time to investigate the matter because Ms Rodgers' last time was four years ago.

Should they catch the culprit, the person could face life imprisonment under the under the Misuse of Drugs Act.

"I still can't believe it was drugs. I wonder if they were going to try to retrieve it. I'm sure they would have wanted it back. I wonder if they followed me," Ms Rodgers said.

"I could've been picked up at the airport. Or if I'd gone through somewhere like Bali or Thailand with that in my bag ... terrifying."