A series of vigilante attacks targeting alleged motorcycle thieves in the Mexican city of Lagos de Moreno has sparked a national debate about criminal justice.

The nighttime activities by the unidentified perpetrator or perpetrators, nicknamed the “Batman of Lagos de Moreno” on social media, were apparently intended to intimidate and humiliate the targets.

Between June 12 and June 19, a total of five people were left beaten and tied to lamp posts with large amounts of duct tape, with the word “rat” in Spanish written on their foreheads. One person had his pants pulled down, according to images circulating online. In one case, two young men were tied to the same post.

Bright pink banners explaining their alleged wrongdoing were taped above the people’s heads, while the motorcycles they allegedly stole were parked at the scenes.

The Jalisco state prosecutor’s office has confirmed it is investigating the series of attacks, stressing that the targeted men are considered victims.

Supporters of the “Batman” have argued that a comic book-style hero meting out justice to small-time criminals outside the law is what Mexico needs, as the authorities are focused on fighting far more dangerous drug cartels. Opponents have called vigilantism “barbaric” and a symptom of a dysfunctional society.