From this:

New guidance telling U.S. Immigration and Customs Enforcement agents to focus on apprehending terrorists and criminals has many of ICE's rank-and-file agents wondering who then is responsible for tracking down and detaining the millions of other illegal border-crossers and fugitive aliens now in the country.

The new guidelines are outlined in a June 29 memo from Assistant Secretary John Morton, who heads the agency, to all ICE employees regarding the apprehension, detention and removal of illegal immigrants, noting that the agency "only has resources to remove approximately 400,000 aliens per year, less than 4 percent of the estimated illegal-alien population in the United States."

...More than a dozen veteran ICE agents told The Washington Times in the past week that the carefully worded memo had field agents wondering whether they would be detaining illegal border-crossers in the future and whether those apprehended by other law enforcement agencies would be turned over to ICE for eventual deportation.

Related: a John Morton quote about ICE refusing to deport illegal alien students.