Phoenix police say the human remains found at a construction site near 87th Avenue and Indian School Road appear to be those of an infant.

There are 40,000 unidentified sets of human remains currently in this country.

“It's only possible to identify someone if there’s someone looking for them,” said Anthony Falsetti, Ph.D., a forensic anthropologist and professor of practice at Arizona State University.

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It's a slow process from discovery to identification that in many cases takes weeks, even months to complete.

Falsetti breaks it down into three parts:

1. Recovery after the discovery

"There are more skeletal elements to deal with the younger the person is. The ends of the bones aren't fused together so for example, one bone may actually be three. So it could vary from over 500 to the adult 206. It's more labor intensive -- you have to be very detailed in your analysis."

2. Examination and documentation in a lab

"Lay out the body as a skeleton. It's a process of identifying what bones are what and then they would photo-document, take handwritten notes and then they would begin their assessment and that assessment would be, in a younger adult, primarily measuring. So they measure all the long bones so they could estimate age as well as stature. Look at the dentition, any of the teeth that are there."

"They would probably want to use some fairly low-resolution microscopy, microscope, and just look at the surface of the bone for any areas of possible trauma."

3. Additional testing, such as DNA

"The sex of the individual, so they would look for presence of the Y chromosome."

"They would want to develop the profile, the biological profile, the molecular profile of this person and depending on the lab, it'll probably be 13 characteristics they're going to try and determine what they are."

Scientists can try and match that up through a DNA database. Parents of missing children usually have their DNA in that database for that reason. Which comes back to Falsetti's point that "it's only possible to identify someone if there’s someone looking for them."

Falsetti says children typically have a higher chance of being identified “because more people are interested in missing children.”