Police in Rome are searching for a possible serial killer after the bodies of three women were found in two apartments in the prestigious Prati district.

Two women, two sex workers of Chinese descent between the ages of 40 and 50, were found stabbed to death in an apartment on Via Augusto Riboty.

The doorman of the house raised the alarm after finding the body of one of the dead women on the doorstep of the apartment Thursday morning, and the other body was found inside.

The body of a Colombian woman identified as Marta Castano Torres, also a sex worker who had been stabbed to death, was found by her sister in the basement of an apartment on a nearby street.

The bodies of the Chinese women were found with stab wounds to the throat, chest and back, and their identities have not yet been determined.

A Rome police source said investigators are working on the theory that the women were killed by the same person. Torres, 65, who, according to Italian press reports, worked as a prostitute to financially support her daughter, is believed to have been killed before the other two victims.

The murders took place a few hundred meters from the Italian Supreme Court, in an upscale neighborhood but where criminal networks engaged in apartment prostitution have grown in recent years.

The murders have sparked calls for prostitution to become a regulated profession in Italy to protect industry workers. Street prostitution is legal in Italy, but organized prostitution and brothels are illegal, The Guardian writes.