Spanish police have arrested 22 alleged pimps in connection with a prostitution ring in Madrid -- and some even allegedly tattooed women they forced into prostitution as a sign of "ownership," the Associated Press reports.

The Daily Mail notes one 19-year-old woman held against her will had a bar code and an amount of money tattooed on her wrist by her pimp. Sex workers were allegedly inked with the distinct marks after escape attempts to denote their "owners" and how much money they owed their pimps, the paper writes. The freed woman claims to have been whipped, chained to a radiator and having had her hair and eyebrows shaved off as punishment from her illicit proprietor, according to the AP.

Police are referring to the gang as the "bar code pimps," according to reports, and 22 suspected pimps have been arrested, all of Romanian nationality. In addition to the arrests, police seized more than $185,000 in cash, illegal firearms, swords, machetes, gold jewelry and luxury vehicles, CNN notes.

One of the ring leaders, by the name of Iancu T., was also wanted in his country for crimes related to prostitution, La Razón reports. Iancu allegedly made false promises of legitimate work to women to ensnare them, only to force the women into prostitution in various clubs throughout the community of Madrid as well as along Calle Montera, a street in central Madrid. According to Spanish newspaper ABC, Calle Montera holds an infamous reputation for hosting dozens of prostitutes at all hours in the heart of Spain's capital.

Iancu and the two clans implicated in the bust often called their sex slaves "packages," "suitcases" and "bicycles," according to CNN. The pimps monitored their "packages" on Calle Montera from a number of apartments they owned and used for turning tricks, La Razón notes.

AP reports sex trafficking is a multi-billion dollar industry in Spain, where the legalities of prostitution fall into a legal grey area. Pimping is outlawed, while prostitution is not regulated. Most of Spain's sex laborers are poor immigrants from South America, Africa and Eastern Europe.

Clarification: Language in the headline and throughout the article has been amended to better indicate that the women were victims of sex trafficking.