Police have turned up bones and other evidence under the floor of a dwelling near Mexico City where a man was arrested for allegedly stabbing a woman to death and hacking up her body.

Prosecutors in the State of Mexico, which includes most of the capital’s suburbs, said late Wednesday they cannot yet determine the number of possible victims, and that DNA testing will be needed.

But evidence like shoes, ID cards, women’s handbags and clothing found at the slum dwelling just northwest of the capital suggests the 72-year-old suspect may have been a serial killer and that he may have been slaughtering victims for years.

Investigators used jackhammers to tear up a concrete floor and officials had to partly dismantle the spare structure made of concrete block and tin roofing to allow forensic experts to sift through dirt at the site.

The dwelling is located on a common-access property in which several dwellings were built on a single lot. On Tuesday, prosecutors said they arrested a 72-year-old man there, while they were searching for a missing 34-year-old woman.

Once inside the dwelling, police found a sort of shallow basement, and in it a bloody table with the woman’s hacked-up body.

But just as chillingly, investigators found ID cards, women’s makeup, bags and clothing, as well as notebooks and videocassettes marked with the names of other women.

The stocky, short man has been identified only as “Andrés” under Mexican laws protecting a suspect’s identity. He appeared to walk haltingly as he was escorted to jail, where he is being held on possible homicide charges.

Mexico has seen a wave of women’s killings in recent years and activists say police do not do enough to prevent, investigate and prosecute such crimes.

In 2018, a man was arrested in another Mexico City suburb and confessed to killing at least 10 women. Prosecutors said at the time he may have sold the bones of some of his victims.

The grisly case was uncovered after a couple was caught carrying dismembered human remains in a baby carriage.