Washington ? Ten days after a splashy 26-state immigration raid netted 1,187 arrests, about one in three of those apprehended are back on the streets, reflecting a fact of life that immigration officials say they live with every day.

“It’s frustrating. It’s complicated,” said Dean Boyd, a spokesman for Immigration and Customs Enforcement. “But those are the cards we’re dealt.”

The complex, multiagency raid April 19 on 52 worksites operated by IFCO Services, a Dutch-owned pallet service company, was the largest such investigation and operation ever undertaken by immigration agents, according to federal authorities.

But a look at what’s happened to those taken into custody last week, say experts familiar with the system, reflects the problems of immigration enforcement as much as the operation’s success. About 270 have been deported voluntarily. Roughly 460 of those arrested are still behind bars – some awaiting immigration proceedings, some being held on prior warrants and some unable to make bond. Another 50 have been referred to other agencies, mostly in law enforcement, Boyd said.

For a variety of reasons, another 400 of the illegal workers arrested already have been processed and released – some because they have families living with them or no criminal records or they are needed for witnesses – often on a promise to appear in court when they are asked.