The Department of Homeland Security raised eyebrows last week when it released more than 2,000 illegal immigrants facing deportation from detention, fueling speculation that the Obama administration had timed the move to play up the impact of sequestration.

The administration quickly pushed back against the criticism: DHS Secretary Janet Napolitano said this week that the decision was made independently by the department's Immigration and Customs Enforcement, without guidance from the White House. And she denied that all of the releases were due to budget cuts, claiming that the move was routine. "We are constantly...moving people in and out of detention," she said at an event on Wednesday.

What's really going on here? It's not entirely clear. On the one hand, ICE has explicitly said that "fiscal uncertainty" and the looming sequester prompted ICE officials to identify detained immigrants for release. However, the agency isn't currently able to specify how many were placed into non-detention alternatives — though it promises to make that determination soon.

"ICE does not maintain records on whether an individual was released primarily for budgetary reasons," says ICE spokeswoman Gillian Christensen. "ICE is conducting a review in order to identify which individuals were released due to normal fluctuations and which were released primarily due to the budgetary pressures of the continuing resolution and the sequester."

Some immigration policy advocates believe, however, it's clear that the release was out of the ordinary. "I can't think of a time where they did something all in one fell swoop," says Marshall Fitz, director of immigration policy at the Center for American Progress. "It was clearly sequester-precipitated, and it wasn't in the normal course."

Others say there's just not enough data to determine whether or not the release was out of the ordinary and say, anecdotally, that there hasn't been a drastic change. "To be honest, we've had a lot of difficulty getting precise information," says Megan Bremer of the Lutheran Immigration and Refugee Service, which has field offices throughout the country to protect and advocate for immigrants. "We're not having a lot of alerts from the field that there's a huge spike in the numbers."

While there's a debate over the scale of the release, advocates and experts generally agree that the move reflected the Obama administration's stated policy of prioritization the detention and deportation of criminal immigrants who posed a threat to public safety, and to explore the use of non-detention alternatives for those that didn't.

There was a record 430,000 immigrants placed in detention at some point last year, but the number of those placed under alternative monitoring also increased, says Muzaffar Chishti, director of the Migration Policy Institute's office at New York University. The number of immigrants released from detention into alternative monitoring rose 25 percent in 2012, from 20,000 to 25,000, according to Chishti's calculations. "There's been a recent receptivity to using this program [of detention alternatives]," Chishti says.

The difference this time is that the administration seems to be looking more systematically to determine whether or not detained immigrants need to remain there, or whether it would be more cost-effective to put those that don't pose a threat under electronic or telephonic monitoring, among other alternatives.

(AP Photo/Alan Diaz) (AP Photo/Alan Diaz)

"I haven't seen it ever where it's done like this, where they're doing a scan of the population that's in detention and from that scan, making a decision whether or not to release them," Fitz says. Bremer points out the administration's recent commitment to using a uniform set of recommendations — known as a "risk assessment classification" — to make that call. "It's a more systemic way to determine whether or not someone should be detained," she concludes.