Police on Wednesday identified the remains of two women among 13 bodies unearthed during a desert excavation outside Albuquerque.

Police used dental and medical records to confirm the identities of Cinnamon Elks, 31, and Julie Nieto, 23, both Albuquerque women who disappeared in 2004. Two other women whose remains were identified earlier, Michelle Valdez and Victoria Chavez, also disappeared from the city in 2004.

"With these additional identifications, this obviously gives a great deal more of information for the investigative team to follow up on," Police Chief Ray Schultz said Wednesday at a news conference. "Now instead of trying to cross the life paths of two individuals, we have four individuals that we can try to see what was going on in their lives when they were reported missing."

Elks and Nieto had been arrested numerous times for prostitution and drug possession. Police said Valdez and Chavez suffered drug addictions and worked as prostitutes when they were reported missing.

The four were among 16 women reported missing between 2001 and 2006. Valdez was 22 and had two children, with a third on the way. Chavez, who was about 28 when she vanished, had a daughter.

The excavation began in February, when a hiker discovered a single human bone. The remains, including Valdez's fetus, were found in an area that had been razed for a housing development.

"This is obviously a very large crime scene and we still have a lot of work to do," Schultz said.

Investigators were using equipment and rakes to sift through the dirt for more remains, since four of the unearthed bodies were not complete, he said.

"Almost every day we have found something," Schultz said. "Very often, it's a small bone. In some cases it's nothing other than a single vertebra."

The remains are being turned over the Office of the Medical Investigator, which is helping police make identifications.

Schultz said investigators didn't know who buried the bodies at the site, but they had set up a national hot line and were receiving help from federal authorities.

"Anything is possible," he said. "This could be the act of a single person, this could be the act of two or more or it could be an organized group. We just don't know yet."