WATERLOO - Officials concluded initial appearances for Agriprocessors employees charged in criminal court shortly before noon Thursday, and began moving those detainees from the National Cattle Congress grounds.

In all, a total of 306 people detained in Monday's raid on Agriprocessors have now been arrested on criminal charges, including 281 men and 25 women. They were part of a re-estimated total of 389 individuals administratively detained during the raid, said Matt Dummermuth, U.S. attorney for the northern district of Iowa.

Those detained on criminial charges are being held by U.S. marshals in local jails.

Wednesday was the last night detainees were housed overnight in Estel Hall on the NCC grounds, said Claude Arnold, special agent for U.S. Immigration and Customs Enforcement. All detainees not arrested on criminal charges will be held in ICE custody at local jails.

Status hearings on the criminal cases have been set for next week at temporary court facilties in Waterloo, at the NCC's Electric Park Ballroom.

Of the 389 administratively arrested, 62 were released on humanitarian grounds and 21 are being held on administrative charges. Of the 83 released on humanitarian grounds or held on administrative charges, 18 were juveniles ages 13 to 17 who were either released to a adult or turned over to the Office of Refugee Resettlement.

Those who do not face criminal charges will be placed into administrative immigration removal proceedings conducted at other locations.

"This has been an unprecedented undertaking in nearly all respects," Dummermuth said, noting federal agents, law officers and his staff "have worked literally around the clock" to process the cases. "To have this completed in three days is phenomenal."

ICE agent Arnold said, "We worked closely with the U.S. Attorney's Office and with attorneys representing the detainees to ensure detainees rights were fully protected."

Most were sent to local jails pending their next hearings. However, federal agents are staying put at the NCC detention grounds.

Prosecutors hint that the largest immigration raid in U.S. history may have another chapter.

"The investigation is ongoing," Bob Teig, a spokesman for the U.S. attorney's office, in Cedar Rapids, said Thursday.

Authorities were to remove the last of the detainees from the National Cattle Congress grounds by Thursday night, said Tim Counts, an ICE spokesman.

However, Counts wasn't able to say when ICE officials would be leaving the NCC grounds. The federal government's lease extends through May 25.

"We're hearing lots of rumors about whether they're going to do further follow-up action … or whether they're going to go into another facility," said Lori Chesser, a member of the American Immigration Lawyers Association. "There's all kinds of rumors about that, but of course we have no idea what they'll do."

Immigration and Customs Enforcement agents arrested the 389 people Monday at the Agriprocessors meatpacking plant in Postville, most from Guatemala and Mexico. A majority were taken to the NCC fairgrounds to await court proceedings. A temporary courthouse on the grounds had been bustling with detainees making their initial court appearances.

Following the raid at the Postville plant, 306 workers were charged with crimes ranging from misuse of Social Security numbers to identity theft, said Teig.

ICE will continue to operate part of the housing unit at NCC as a holding area for defendants returning from jails for court hearings, Counts said.

Criminal courtrooms will remain open in the Electric Park Ballroom area for status hearings and possible pleas, said Clerk of Court Robert Phelps. Counts said said the Electric Park courts will be used for criminal charges and not immigration matters.

Teig has acknowledged further arrests are possible but has not said whether company officials are being investigated. He noted that the raid included 697 arrest warrants, which means agents could have more work to do.

Read Friday's Courier and online updates for more details.

Contact Jeff Reinitz at (319) 291-1578 or jeff.reinitz@wcfcourier.com.