Locked in a high-security storage room on campus lay the remains of some 6,000 people.

They are not the remnants of a violent crime scene or mass disaster- they are pieces of history dating back to prehistoric times.

The latest addition to the Arizona State Museum's collection of human remains, a near-complete female skeleton uncovered at a construction site on Tucson's northeast side, continues to be examined by researchers who hope to solve the mystery behind the bones.

Grading equipment displaced the century-old remains Jan. 19 while preparing land in the 8400 block of East Tanque Verde Road for construction of the Rincon Mountain Presbyterian Church.

The discovery was referred to the museum for study after the Pima County Medical Examiner's Office determined that the bones were more than 50 years old and therefore not connected to any recent criminal activity.

Ongoing assessment has shown the bones to be those of a female guessed to be in her 30s or 40s, said John McClelland, lab manager of osteology at the museum. Remnants of a safety pin among the remains suggest that the woman was alive after 1849, when the safety pin was invented.

"It's probably turn of the century, maybe a little bit later," McClelland said.

Scott Doty, an anthropology senior who helped excavate the site where the body was found, called the discovery "amazing" but also upsetting.

"It's sad to see something be so forgotten that to be rediscovered it has to be bladed in half by a giant machine," Doty said.

While much of the body's skull was missing - which McClelland said was probably the result of a run-in with the grader - it is one of the more complete sets of remains in the museum's collection.

However, this is one museum collection the public will likely never get to see.

Of the museum's 6,000 sets of human remains - some complete and some incomplete - most are considered prehistoric, meaning that they date back prior to the arrival of Europeans in America, McClelland said, and most have been determined to be American Indian.

While 50 years ago the bones might have headlined a museum exhibit, today they remain behind closed doors partly out of respect, McClelland said.

"If you look in papers in the 1970s, (there are) pictures of Native American burial excavations," McClelland said. Since then "many tribes have requested (privacy) and no photographs."

A federal law passed in 1990 requires all federally-funded museums to report any historical human findings so that American Indian tribes have the option of reclaiming the remains and giving them proper reburial, McClelland said.

All the museum's remains are subject to repatriation if a legitimate affiliated party comes forward to claim them, and those that go unclaimed remain under museum protection, and the museum director has the option to rebury them.

Museum researchers and community specialists who have access to the bones and artifacts treat them delicately and forego the costly "CSI"-style techniques of DNA tests and scientific sampling, McClelland said, opting instead for the most basic tools - including a magnifying glass and caliper for making measurements.

While the museum is not actively looking for additions to its collection of remains, McClelland said several "inadvertent discoveries," like the one in the Tanque Verde area, are made each year.

McClelland said the most recent discovery is far less common than the usual American Indian finds.

The body, found in a decomposing wood coffin, was the only skeleton found at the site, and McClelland said he suspects her family might have buried her there before moving to another place.

"There's no evidence of any other graves," McClelland said. "It's a little unusual to have only one."

A rosary amongst the remains suggests she was Christian and probably Catholic, McClelland said.

While the race or ethnicity of the body has not been determined, efforts are being made to locate anyone who might have a connection to the woman.

Homer Thiel, a historic archeologist from Desert Archaeology Inc., who is assisting the museum, uncovered statistics from land records and the 1900 U.S. Census showing a stock-herder named Thomas Bullock lived on the Tanque Verde property at the turn of the century.

A Hispanic family, the Aguilar family, was referenced in documents as Bullock's "neighbors," and Thiel believes the Aguilar family might have lived on Bullock's property as employees.

Although there is not yet proof that the uncovered remains are connected to either name, Thiel said he suspects that the woman might have been a servant for Bullock, who was unmarried, or an Aguilar family member or friend.

While Thiel was unable to identify the actual person whose remains were found, he hopes that his findings are a step toward solving the mystery.

"One goal of this research is to draw attention to these people and this property and see if someone remembers something," Thiel said.