The detention policies of the Immigration and Customs Enforcement agency in Colorado and the network of facilities that has grown here in the last few years are drawing increasing attention among local lawmakers and human rights organizations. Critics of the system say men and women held on suspicion of immigration violations in the state are housed in conditions that rival those established for violent criminal offenders, that the immigrants are becoming fodder for a booming detention industry, and that detainees are often difficult to locate in the tangle of state facilities, which include unlisted so-called subfield offices.