They approach their quarries who have just got off a plane, bus or train, tap them on the shoulder, sleeve or arm, and ask if they need help.
Before he or she knows it, the victim has parted with some cash, jewellery and their Blackberry - ostensibly willingly.
The criminals who hypnotise these unsuspecting prey - and cause them to lose self-control for anything from seconds to several minutes - are hardly caught.
Such methods are not new, but they tend to spike around this season of Hari Raya Aidilfitri, when close to 10 million residents leave and return to the greater Jakarta area.
To stem the trend, Indonesian police have rolled out banners at airports and play reminders over the sound system at bus terminals and train stations to warn travellers returning to Jakarta after the Hari Raya break to be on the lookout for hypnotist crime. While it is not the first time police have done this, the banners are more ubiquitous and the message is more specific now as anecdotes of incidents appear to rise.
"Be wary of strangers who suddenly touch you and avoid talking to them," a banner outside the arrival hall of the capital's Soekarno-Hatta airport reads.
The website of Jakarta's police department also offers eight tips for people to fight criminal hypnotists. They include being confident one will not be swayed, and being careful if one suddenly feels dizzy or giddy as someone might be forcing that condition on them.
National police spokesman Inspector-General Ronny Sompie told The Straits Times that the nature of such crime makes it difficult to gather evidence and those who do get caught are charged with cheating or theft.
"The perpetrators also plan their acts," he said. "They target those who appear vulnerable - with a lot of luggage, or who ask for help when they arrive."
"That's why vigilance helps, and travellers can also pray that they remain alert to such wiles," he added.
On Monday, Jakarta police said 173 criminal incidents were reported between Aug 2 and 11 - mainly aggravated theft or theft from motor vehicles - and that offences may rise as commuters return over the coming week.
But Mr Ronny noted that victims may also be reluctant to report crimes against them.
Last month (July 27), 35-year-old alleged hypnotist Dian Anggraini was arrested at Batam's Hang Nadim airport with over 40 million rupiah (S$4,900) in cash, gold jewellery and several mobile phones after a victim's child recognised her, Batam media reported.
She claimed she did not use hypnotism, but said the victims had placed their trust in her.
Crime analyst Mardigu Wowiek Prasantyo told The Straits Times there is often a logical explanation for how people fall prey to hypnotists.
"In hectic environments like airports and terminals, it is very easy for someone to be distracted. It's like your brain 'hangs', and what these criminals do is 'flood' your mind by touching and talking to you," he says.
"When you are touched, your focus shifts and you are not fully aware of your immediate actions."
"If you're already easily distracted, the best prevention is to keep a distance from strangers, so you don't have a chance to fall under their spell," he adds.
