SALT LAKE CITY (AP) – Attorneys for a southern Utah math teacher facing multiple felony charges in the illegal trafficking of American Indian artifacts said Thursday that they have reached a plea agreement with federal prosecutors.

David Lacy, of Blanding, was one of 26 people indicted in Utah, New Mexico and Colorado on artifacts looting and trafficking charges after two-year undercover investigation by federal authorities. Lacy was set for a six-day jury trial July 11.

The case broke open in May 2009 when about 150 federal agents descended on homes in the Southwest's Four Corners region. It's been touted by officials as the largest-ever investigation into archaeological thefts.

In Utah, agents raided residences in the small town of Blanding, arresting 16. Those arrested – including Lacy, who is the brother of San Juan County Sheriff Mike Lacy – were handcuffed and shackled as agents confiscated stone pipes, woven sandals, spear and arrow heads, seed jars and decorated pottery.

The cases hinged on the work of confidential government operative Ted Gardiner, an acknowledged artifacts expert and dealer, who arranged dozens of deals and recorded the transactions on tape.

Lacy was indicted on accusations that he sold a woman's prehistoric loin cloth, a turkey feather blanket, a decorated digging stick, a set of knife points and other artifacts for more than $11,000.

He pleaded not guilty to the charges and, until Thursday, it appeared his would be the only case to go to trial.

Two of the 26 defendants – Steven Shrader, a Santa Fe, N.M., salesman and James Redd, a prominent Blanding, Utah, physician – committed suicide after their arrests.

Each of the other defendants, including two co-defendants charged alongside Lacy, reached plea agreements with federal prosecutors. None has been sentenced to prison.

Lacy fought the charges in part because a felony conviction could disqualify him from his job as a high school teacher.

On Thursday, both Lacy's attorney, Matthew Lewis, and Assistant U.S. Attorney Richard McKelvie declined to comment on the details of the “agreement in principle” they had reached.

McKelvie said a change of plea hearing will be held in July, although no date has been set.