She is a psychological science undergraduate who sometimes buys and sells on online marketplace Carousell.

But to some buyers on the platform, Ms Mandy Teo, 21, is known as the fraudster who dupes people into paying for coveted tickets.

These tickets are for entry to the popular annual Halloween Horror Nights by Universal Studios Singapore (USS), among other events.

Each ticket to the Halloween event costs $68, but those sold on Carousell are usually cheaper.

A woman even turned up at Ms Teo's Pasir Ris home on Tuesday, asking for tickets which she had paid $250 for.

However, Ms Teo had neither the tickets nor any inkling of these deals, as she had been a victim of identity theft. Ms Teo told The Sunday Times the woman had wanted the tickets for her daughter.

"She said this was the address given to her by the scammer and she had already transferred the money," said Ms Teo, whose parents had answered the door at that time as she was not at home.

Ms Teo lost her identity card last year and had it replaced early this year. But last week, the James Cook University student got a rude shock when a friend told her that a scammer has been using her lost IC multiple times to sell entry tickets.

Her friend's acquaintance was one of the victims, she added.

The fraudster had prowled for victims on Carousell and Facebook and sent a photo of Ms Teo's IC to buyers as "proof" of identity.

But as soon as the fund transfer for the tickets was made, the scammer would disappear and block all contact. Said Ms Teo: "I felt that it was very unfair (to me) as I did not do this, but my IC was (being used) everywhere."

Between 2012 and 2016, an average of 32,000 people a year have reported losing their ICs, according to figures by the Immigration and Checkpoints Authority (ICA).

Early this month, the police had raised concerns over the rise in USS Halloween ticket scams this year, with victims losing a total of $21,500 so far. There were at least 35 reports of such online purchase scams between Aug 30 and Sept 29, compared with 30 cases last year.

Ms Teo wrote a Facebook public post on Oct 8 to set the record straight. Her post has been shared more than 1,600 times.

Four victims have since reached out to her. One had paid about $325, she said. The scammer's Carousell account has been reported and suspended. Ms Teo made a police report on Tuesday.

Cases of identity theft usually fall under cheating or offences under the Computer Misuse and Cybersecurity Act.Singaporeans are required to report the loss of their ICs and apply for a replacement card personally at the ICA Building within 14 days.

As the scammer may still be using her identity under another account, Ms Teo said she cannot rest easy until the culprit is caught.