Cancun police picked up four men and one woman on October 12 in Supermanzana 63, a residential block away from the hotel zone's resort strip, and what started as a drug bust has turned into a counterfeiting investigation. The State Attorney General's office (FGE) says the group — all Cuban nationals aged between 21 and 44 — is now being probed for allegedly circulating fake Mexican pesos around the city.

Officers conducting the operation seized small bags of plant matter resembling marijuana and a substance believed to be crystal meth, along with a 4.5mm handgun loaded with three rounds. But the detail that has drawn the attention of prosecutors is the 8,600 pesos in suspected counterfeit bills found in the group's possession. Two vehicles and several mobile phones were also confiscated.

Those in custody have been named by authorities as Yanisleidis, 21, José Antonio, 44, Deivys, 42, Bryan, 28, and Yandry, 42. All five were initially detained on suspicion of small-scale drug trafficking; the counterfeiting probe came after investigators linked them to fake currency already in circulation.

For the millions of visitors who pass through Cancun each year, this is the kind of story that sounds alarming but barely touches the average traveller. Counterfeit peso notes are a known risk anywhere in Mexico, and the practical defence is simple: check your banknotes for the security features — watermarks, raised printing and the security thread — particularly if you receive 200 and 500 peso bills in change at markets, taxi stands or beach vendors. Larger shops and hotels handle cash through counted systems, so the risk there is low.

It's also a reminder that Cancun is a working city of nearly a million people, with neighbourhoods like Supermanzana 63 far removed from the tourist corridor. Crime involving fake money and small-scale dealing occasionally touches foreign visitors, usually through accepting a bad note, so a few seconds of scrutiny can save you a real loss — knowingly passing counterfeit currency is an offence in Mexico, regardless of who handed it to you.

If you're travelling in the area, keep a small amount of pesos for street purchases, prefer card payments where possible, and exchange money at banks or licensed casas de cambio rather than informal sellers. The handful of people arrested this week are in custody facing drug and potential counterfeiting charges; the investigation by the FGE is ongoing.