Updated

Authorities have made arrests in the 2010 theft of about $80 million in prescription drugs from a Connecticut warehouse, a robbery described as one of the biggest pharmaceutical heists in history, the U.S. attorney's office said Thursday.

The U.S. attorney's office, FBI and Enfield Police Department planned to hold a news conference Thursday afternoon to discuss the unsealing of an indictment and arrests of those allegedly involved in the theft.

The thieves broke into the Enfield warehouse of pharmaceutical giant Eli Lilly & Co. in March 2010 and stole enough pills to fill a tractor-trailer. The drugs were believed to be destined for the black market, perhaps overseas.

After cutting a hole in the roof of the industrial park warehouse, they lowered themselves to the floor, disabled the alarms and spent at least an hour loading pallets of antidepressants and other drugs into a vehicle at the loading dock, authorities said. The company said the stolen drugs included the antidepressants Prozac and Cymbalta and the anti-psychotic Zyprexa.

In the days after the heist, the Indianapolis-based drug maker asked the public for help in spotting the stolen pills and warned consumers to watch for tampering that might indicate products were stolen. Local police interviewed company workers and checked area hotels to try to identify suspects, but there was little word on progress of the investigation until now.

Experts have said the heist shared many traits with warehouse thefts of pharmaceuticals last year near Richmond, Va., Memphis, Tenn., and Olive Branch, Miss. Those thieves also cut through ceilings and sometimes used trapeze-style rigging to get inside and disable the main and backup alarms. In some cases, they sprayed dark paint on the lenses of security cameras; in others, they stole disks in the security recording devices.