A federal program to work with local law enforcement to remove dangerous illegal immigrant criminals, implemented just weeks after Kate Steinle's murder put the issue in the national spotlight, has resulted in fewer deportations, according to analysts.

The Priority Enforcement Program (PEP) was introduced last summer as something of a compromise to get sanctuary cities to work with the federal government on deportations by only requesting that local authorities hand over the most dangerous criminals. Statistics show that fewer local law enforcement agencies are refusing to work with Immigration and Customs Enforcement, yet far fewer illegal immigrant criminals are being deported under the current scheme.

“The end result is that ICE has not improved its performance through its detainer program in apprehending individuals who the agency seeks to deport,” stated a recent report by the Transactional Records Access Clearinghouse, a data research organization based at Syracuse University.

Sanctuary cities, the broad term for more than 200 state and local jurisdictions that have policies barring cooperation with ICE, came under intensified fire after the July 1, 2015, murder of Steinle in San Francisco by an illegal immigrant who had recently been released from local custody. By law, local law enforcement agencies are supposed to turn illegal immigrants over to the feds for deportation when they are due to be released from custody, but illegal immigration advocates say the policy violates the subject’s civil rights.

Republicans in Congress, as well as GOP presidential nominee Donald Trump, have called for cutting off federal funding to sanctuary cities.

Jeh Johnson, secretary of ICE’s parent agency, the Department of Homeland Security, announced PEP was taking effect on July 30, 2015, saying it replaced a previous system under which ICE ordered local law enforcement agencies to hold and turn over all illegal immigrant criminals eligible for deportation. In addition to not garnering local cooperation, the older system meant non-violent criminals or those merely suspected of crimes could be deported if they were here illegally.

“The President and I want to better focus our immigration enforcement resources on convicted criminals over undocumented immigrants who have been here for years, have committed no serious crimes, and, have, in effect, become peaceful and integrated members of the community,” Johnson said.

Instead of issuing “detainers,” or federal orders to hold and hand over illegal immigrant criminals and suspects, ICE now lodges I-247s, or “requests for notification.” Those requests are more likely to be honored, TRAC’s studies show, partly because they are made less frequently and cooperation does not mean actually turning over a subject.

“ … Outreach efforts have drastically curbed reported refusals by law enforcement agencies to transfer custody of individuals over to ICE,” the TRAC report stated, before adding, “the proportion of occasions where ICE took custody of the individual after issuing I-247 requests has not rebounded. Indeed, this rate has continued to decline.”

In addition, ICE often lodges a request to be notified of a pending release, but never acts on it, according to the report. During the first two months of 2016, ICE failed to assume custody of more than 60 percent of individuals it had requested notification on. In 2009, the figure was about 30 percent, according to TRAC, which called the drop “startling.”

Critics of PEP have long objected to the idea that only violent or dangerous illegal immigrant suspects should be ticketed for deportation when they cross paths with law enforcement. The federal government is obligated to remove anyone who is here illegally, said Dan Stein, president of Federation for American Immigration Reform.

"Prioritizing the removal of the most dangerous and violent criminal aliens should not mean exempting all other immigration lawbreakers from enforcement,” Stein said. “The administration is using the pretense of focusing on hardened criminals to advance its real priority: granting de facto amnesty to the vast majority of illegal aliens."

By prioritizing only those illegal immigrants who have proven they are dangerous, the federal government is effectively waiting for suspects to graduate to violent crimes, said Jessica Vaughan, director of policy for the DC-based Center on Immigration Studies.

Vaughan cited the case of Sarah Root, who was killed in a car crash in Omaha, Neb., in January after Eswin Mejia slammed his car into hers while he was intoxicated and drag racing. Mejia is an illegal immigrant who arrived into the U.S. as an unaccompanied minor, and who had several previous brushes with the law, said Vaughan.

“The local detectives asked ICE five times for a detainer on Eswin Mejia, but ICE said that he was not a priority for enforcement because he had not been convicted of a serious crime,” Vaughan said. “He was released on bail and disappeared, and is now on ICE’s most wanted list. It was a major scandal for ICE.”

In another instance, Johnny Josue Sanchez, 21, a Honduran national in the country illegally who had been arrested three times, allegedly killed five homeless people when he set fire to a vacant building in Los Angeles. In this case, Vaughan said the combination of ICE’s and Los Angeles’s disinterest in removing Sanchez after so-called previous “minor” offenses resulted in tragedy.

In yet another case, Marilyn Pharis, a 64-year-old Air Force veteran, was brutally raped and bludgeoned to death with a claw hammer on July 24, 2015, in her own home. Victor Aureliano Martinez Ramirez, 29, an illegal immigrant from Mexico who was arrested six times in the previous 15 months, was one of two men charged in the case.

“All of these deaths were preventable,” Vaughan said. “ICE should not be waiting for deportable aliens to commit murder before enforcing immigration laws, and local jurisdictions should be cooperating fully in order to spare their citizens from becoming victims of people who should not be here to begin with.”

Department of Homeland Security officials did not return email inquiries to FoxNews.com about this report.