Authorities say bones from 13 victims have been recovered from a desert site west of Albuquerque that authorities have been excavating for about a month.

The death toll had been 11, but police said that further examination of the remains Thursday showed that they must have belonged to 12 victims. Police recovered a 13th body Friday.

The bones have all been dug up from an area recently razed for a housing development. A hiker made the first grisly find.

Only two sets of remains have been identified.

Authorities say 22-year-old Michelle Valdez and 28-year-old Victoria Chavez of Albuquerque both suffered drug addiction and worked as prostitutes when they were reported missing in 2004.

Police say they suspect the remains were buried by one person, meaning a serial killer could be on the loose.