In March 2014, Kummerfeld came to Hong Kong believing she was getting funds for a water project in Ghana.

Instead, she unwittingly became a drug mule and was caught at Hong Kong airport with 2kg of crystal meth hidden in a bag someone had asked her to take to Australia. After a year on remand, she was set free when the Department of Justice dropped its case against her.

Today, she tells her story of how a woman in her eighties, who is legally blind, found herself at the mercy of the global market for methamphetamine.

"I had never heard of Ice before, I thought it was something you put in Coca-Cola," she said this week.

It was a warm spring day when Kummerfeld arrived in Hong Kong last year.

From her room on the 13th floor of the mid-market Kowloon Hotel in Tsim Sha Tsui, she could peer across to the five-star Peninsula Hotel, a reminder to her of when she spent time in Hong Kong as a toddler in the 1930s.

"Our servants used to stay at the Kowloon Hotel, while we stayed at the Peninsula," Kummerfeld told customs officers during more than two hours of interrogation shortly after her arrest on April 5 last year.

Her story is a tragic example of what law-enforcement agencies worldwide have described as a growing trend of global drug syndicates preying on elderly people and turning them into unwitting drug mules.

Watch: Six alleged drug smugglers cleared of charges in Hong Kong

The victims are just one of the by-products of Australia's - and the region's - appetite for crystal meth, which has surged in recent years alongside a jump in the number of shipments that have been intercepted, either in Australia or at major transit points such as the mainland and Hong Kong.

Born in 1931 in what was then known as Port Arthur in Liaoning province, Kummerfeld was the eldest daughter of a shipping-executive father, and the family moved around coastal cities.

"I remember eating breakfast on the verandah and watching the harbour," Kummerfeld recalled this week of her childhood days at the Peninsula Hotel.

"But it's changed so much now."

Not only had the city changed dramatically when Kummerfeld returned last year, her personal situation was also vastly different.

During 15 years of working at the UN, she had a stint as a special adviser to the undersecretary general for economic and social affairs. With several degrees under her belt, she also wrote two children's books, was a university professor and set up major libraries in New York.

But in 2012, her husband died unexpectedly and she spent most days alone at home, answering emails from strangers seeking money.

During her time with the UN, she worked in Kenya and Ethiopia. This exposure to Africa is what her daughter, Tia, believes made her mother more vulnerable to African scams, "because she could relate to them".

Receiving up to 50 such emails a day, she became a scammer's dream. "She was a jackpot for them because she had money and she had the Africa connection," Tia said.

Over the years, she was swindled out of hundreds of thousands of dollars, usually by wiring cash through Western Union. One scam saw her sending US$25 every week to the "president of Ghana", and other times she would wire up to US$1,000 to a location in Africa.

As her bank account rapidly dwindled, she sold off her jewellery and personal items.

As early as 2010, Kummerfeld received emails linked to the con that eventually led to her arrest in Hong Kong. One of the earliest emails was from a man purporting to be Donald Kaberuka, the president of the African Development Bank.

Kummerfeld questioned his identity, but she continued to correspond with him.

In 2013, she received emails from a Lawrence Smith, who claimed to be a foreign remittance officer for the African Development Bank.

He said she had to go to Hong Kong and Sydney to sign papers to release funds that were to compensate her for money she had previously lost to scammers. That money would then be used to fund a water project for the needy in Ghana.

Again, Kummerfeld poked holes in the odd request, asking why she had to go to those cities when she could sign the papers in Ghana, where the bank is based. But she continued with the plans.

A few days after she arrived in Hong Kong, she received an email telling her that a middleman would deliver a "suitcase of gift items" that she must take to Sydney.

Kummerfeld, not wanting to take a second suitcase, unpacked the items, which included men's clothes and shoes, and put them in a black backpack that was also in the suitcase. This backpack proved to be her downfall.

In her interview with customs officers the day after her arrest, she told them how she lost vast savings to African scams. "I thought we were helping refugee children," she told officers.

She had been scheduled to leave Africa on April 1 but stayed a few more days, as the bank documents were not ready. The hotel booking was extended and the flight changed, with the costs paid by the scammers.

Kummerfeld spent most of her days in the hotel, as she could barely see due to advanced glaucoma. She left her room only to buy food and collect money from a nearby Western Union, from people in Liberia.

On April 5, 2014, she went to Hong Kong International Airport to catch a flight to Sydney, but as she approached the departure gate in a wheelchair, customs officers pulled her aside.

During the interrogation, she described herself as a professional philanthropist. She told how, with the late Elizabeth Taylor and renowned medical researcher Mathilde Krim, they founded the American Foundation for Aids research, also known as amFAR.

When officers told her she was being held for drug trafficking, she became impatient, urging them to catch the people who had tricked her. "We have to hurry up, so we can catch those criminals. While we're sitting here discussing this paperwork, they're running away," she told them.

Asked if she had suspicions about delivering a gift, she admitted it was strange but that "the jungle rules are different", and that she had thoroughly checked the bag for dangerous items.

Later, when she was shown that a tightly wrapped package of crystal meth was hidden in the back compartment of her backpack, she remained adamant.

"I was 100 per cent innocent. I was not aware of the fact the knapsack contained dangerous chemicals," she told them.

Kummerfeld's lawyers applied for bail but the prosecution strongly opposed it - it was a serious allegation and she had no ties to Hong Kong - so the repeated requests were denied.

So for more than a year, Kummerfeld, who celebrated her 83rd birthday behind bars, waited for the courts to hear her case.

On April 30 this year, the Department of Justice suddenly dropped the case, offering no evidence against her. She was acquitted and walked free.

"I was happy and relieved but I did not have strong emotions at all. I knew it was eventually coming," she said of her acquittal.

She has now settled back into her apartment in the US, which is about half an hour's drive from her former Fifth Avenue home. The distance from her past life stretches much farther.

Despite being one of the oldest people to have ever been arrested for drug trafficking, she remains upbeat about her time in a Hong Kong jail.

"When I got arrested, I didn't panic, I was just surprised. I did not resent the handcuffs and I don't think of it as being a victim," she said. "I feel more sorry about the society that has created this world, where people use others."

Shortly after her arrest, American consular officials in Hong Kong informed her daughter Tia.

Desperate to find out what happened, Tia went to her mother's flat and found reams of emails from scammers. "It was clear she had been duped. My mother was a classic scam victim, in that she was getting on in her years and she had stopped working, so she was at home."

When Kummerfeld's husband died in 2012, she lived with a housemate and the online scammers kept hounding her.

"She was philanthropic historically. Even when she was young, she worked for the church making sandwiches for poor kids. It's a very strong characteristic, almost obsessive."

Tia hopes that by telling her mother's story, it will be a warning to others. "This is a serious issue. Elderly people being scammed, and then using them as mules, is despicable."

Barrister Michael Arthur of Gilt Chambers, who represented Kummerfeld, echoed those sentiments. "It's a dramatic example of an elderly person being ruthlessly exploited by a drug syndicate," he said. "She's quite a remarkable woman with a sharp intellect. Why did the Department of Justice drop the case against her? They say in court it was because she had bad eyesight. They didn't offer any reason. It's very unusual."

Despite the tragic events of the past few years, Tia remains hopeful for her mother. "She didn't fall apart in prison, it's amazing. My mother is a strong person, and I can see that she is trying to rebuild her life."

Today, Kummerfeld spends many hours listening to the radio, as she finds it difficult to read because of her failing eyesight. "I crave for conversation and an exchange of ideas."