Archeologists said they've found ancient artifacts that could date back to before the Hohokams in dirt removed from the downtown Phoenix construction site of the Maricopa County Sheriff's Office's $93 million headquarters.

In May, shovels hit an archeological jackpot at the site at Sixth Avenue and Madison Street when workers unearthed remnants of graves that local preservation experts said traced back to Arizona's pioneers who died in the mid- to late-1800s.

The findings were sparse, but coffin handles, wood slivers, and some human remains were discovered, suggesting an incomplete job of moving pioneer remains from the city's first cemetery to the later-constructed Pioneer and Military Memorial Park, an 1881 editorial in the Phoenix Herald and local experts suggest.

But the grindstones and pottery fragments more recently found have been buried for even longer, possibly as far back as 1,600 years ago, experts said.

Mark Hackbarth, an archeologist with Logan Simpson Design Inc., the firm contracted with the county to examine any archeological finds during construction, said the finds date to the Red Mountain Phase, which predates the Hohokam period.

"They're called the Red Mountain Phase by archeologists. That's because there's no way to archaeologically say that's a tribe at that time," Hackbarth told 12 News last week. "They did not have that elaborate of a cultural organization."

The possibility of an additional Red Mountain Phase archeological site is exciting, said Laurene Montero, city of Phoenix archeologist at the Pueblo Grande Museum, where the grindstones and pottery will eventually find a home, per federal law.

"It's an early phase we don't see too much of. There are only a handful of sites we've identified that date from roughly 1 to 300 A.D.," Montero said. "When they find it, it's pretty interesting."

The museum will examine and store the finds for research use and possible display in future exhibits, Montero said.

David R. Abbott, associate professor of anthropology with the School of Human Evolution and Social Change at Arizona State University, who studies the Hohokam, said he will be interested to read the final report when it comes out. A new Red Mountain Phase discovery could tell archeologists why the Hohokam Indians started farming with large irrigation channels, he said, since there's a "direct link" between the two cultures and they were probably ancestors.

Scholars believe the people from the Red Mountain Phase seasonally farmed corn from the floodplains, in this case near the Salt River, Abbott said.

"The finds of that age are pretty rare," Abbott said. "We don't know a lot about the Red Mountain Phase. Any additional information pertinent to what's going on at that time would be of great value."

Montero and Abbott said they are not surprised that artifacts roll in with the dirt as developers dig up downtown Phoenix.

"There is a lot of Hohokam occupation in the downtown Phoenix area," Montero said.

Discovery of the artifacts has put a $200,000 dent in the county's wallet, up from the $2,000 fee the county was paying the archeological firm to remain on-call if anything was dug up, said Maricopa County spokeswoman Cari Gerchick.

The $200,000 expense is covered by an incidental allotment in the $93 million regulating historical finds. After artifacts were discovered, digging in the area stopped for a week while archeologists gathered their findings, Gerchick said, and a report will come out in six months with full details on what was found.

Gerchick said the county is concerned they will receive an additional bill from Hackbarth for talking to the media, so he was silenced by the county after he went on camera to talk about the artifacts.

"Every call he's answering, he's not doing the work the taxpayers are paying him to do," she said.

Gerchick could not provide any details about the artifacts.

"The point is they've got work to do and until that work's done, and their report, information is absolutely preliminary," Gerchick said. "We have no additional information on this part of the project."

Construction of the headquarters forges ahead, Gerchick said. As officials piece together the clues of Arizona's earliest pioneers and artifacts of an ancient culture, a new building goes up in its place.

"There is work on it every day," Gerchick said. "We don't believe that it's behind schedule in any way."