SINGAPORE - Mandy, not her real name, had become a guarantor for a friend.
When he did not pay up, the loan shark came after her and she was forced to become a runner.
And in the end, her friend turned her in and she ended up in jail for two years.
The 64-year-old housewife recalls how her life became hell in 2009 after she became a guarantor for five friends.
Mandy's friends had each borrowed $1,000 from a loan shark.
She says: "So, each of them had to pay an interest of $400 for the $1,000 they borrowed. This is cumulative if they don't repay on time."
They did not settle their debts but the loan shark waited a whole year before he took any action.
And he went after Mandy instead.
She was told: Get your friends to pay up or work as a runner to offset the loans.
It was that or he would go after her son. He did not elaborate on what that meant but it sent Mandy's imagination into overdrive.
Still, it took her a month before she agreed - a decision she kept from her family members.
Mandy started "work" in December 2011, working twice a week.
She says: "I was only told that part of the debt would be offset each time I carried out the work, but he didn't tell me what percentage that was."
She operated in Clementi, Tampines, Bedok and Toa Payoh.
The loan shark provided bicycle chains, padlocks, markers and a mobile phone.
She says: "These would be left in a plastic bag outside my home or the lift landing by other runners and I would be informed through SMS where to pick them up and where to go."
She says she "never threw paint".
"I used only permanent marker pens and wrote "O$P$" (short for "owe money, pay money") on the walls outside the debtors' flats and at the lift landings."
She also padlocked the gates with the bicycle chains and locks.
The loan shark also sent another runner to photograph her in action and the two would often drive to locations in a rental car, also provided by the loan shark.
Mandy says she was extremely stressed during this period.
"I often worried that there might be sick elderly in the flat I had just padlocked. What if they needed medical attention and could not get out?
"Or worse, what if there was a fire in the home and the gate was padlocked by me?"
There were times when she had toyed with the idea of throwing the spare key into the flats so they would be able to get out.
A month and a half after she started working for the loan shark, she was arrested. Mandy had padlocked one of her friend's flats - the same friend she stood as guarantor for - and he called the cops on her.
She says, with a sigh: "I thought I was discreet but soon after, I got an SMS from him and it read: 'I know it was you who padlocked my gate. Just wait for the police to call.'"
Soon after, she got a call on her mobile phone from someone who said he "wanted to pay her for work well done".
It was a police officer.