Prosecutors last week announced a second sanctuary city-related murder case involving an illegal immigrant in the Seattle area, but that has yet to shake local officials who despite the brutality of the slayings say they are not yet ready to begin working with ICE.

The latest homicide was particularly vicious, with police saying Carlos Orlando Iraheta-Vega, an MS-13 gang member, bashed his 16-year-old friend’s head with a baseball bat.

He then assisted as another confederate took a machete to the boy’s body, chopping off an arm and a leg and hacking at his neck.

U.S. Immigration and Customs Enforcement says if local authorities had cooperated with them, Mr. Iraheta-Vega — who goes by the name nickname “Joker” — could have been deported long ago, after an arrest last November.

But King County refused to notify ICE that Mr. Iraheta-Vega was being released from jail, and instead freed him into the community. He would have more run-ins with the law, each time escaping ICE’s clutches, until his arrest last week on suspicion of murder.

That came just a week after another arrest of yet another illegal immigrant, Carlos Daniel Carillo-Lopez, who was shielded multiple times from deportation this year, and who now stands accused of being part of a murder posse that killed a teen after his girlfriend posted an online photo of herself making signs for a rival gang.

Security specialists say both cases are at the crux of the illegal immigration-crime-sanctuary city debate.

Both Mr. Iraheta-Vega and Mr. Carillo-Lopez snuck into the U.S. as juveniles and were deemed Unaccompanied Alien Children (UAC), which qualified them for lenient treatment under American law, earning quick release to sponsors in the community.

Both made their way to the Seattle area where, police say, they hooked up with transnational criminal gangs that increasingly rely on illegal immigrant teens to boost their ranks. They built their own criminal records, all while being shielded from deportation by liberal local governments’ non-cooperation policies.

“This scenario, where sanctuary policies shield criminal aliens who prey on people in the community from immigration enforcement, is becoming all too common,” said Tanya Roman, a spokeswoman for ICE. “As Iraheta-Vega’s crimes increased in severity, local officials chose to release him, time and time again, without notification to ICE, a simple process that could have potentially prevented this crime.”

Police described a horrifying scene of death in the crime Mr. Iraheta-Vega now stands accused of.

The body of 16-year-old Juan Carlos Con Guzman had been bashed with a bat, then chopped to pieces with a machete. Detectives found one of his arms and one of his legs severed and lying away from the body, and also found signs that someone had hacked away at his neck.

Police say Mr. Iraheta-Vega, 20, admitted to the killing, saying he’d arranged to fight Juan Carlos but somewhere along the way he and a fellow MS-13 confederate, nicknamed “Inferno,” decided to kill him instead.

“The defendants beat the victim with a baseball bat and mercilessly chopped his neck repeatedly with a machete before dismembering the body,” prosecuting attorney Mary H. Barbosa told a judge. “The extraordinary brutality of this crime demonstrates the threat the defendants pose to the community.”

In the case of Mr. Carillo-Lopez, police say he was part of a group of Surenos gang members who went looking to fight a boy who had been a friend. They feuded after the boy’s girlfriend posted photos online suggesting fealty to the rival 18th Street gang.

ICE said Mr. Carillo-Lopez had multiple run-ins with police, both before and after the April murder he now stands accused of, yet each time local authorities refused requests to notify deportation agents of his release.

In Mr. Iraheta-Lopez’s case, he was arrested by the Kent Police Department on Nov. 8 for stealing a car and ICE placed a detainer request on him. It was ignored.

Detainers are requests that deportation targets be held for pickup or, at the least, that ICE be notified of an impending release so it can have someone on hand to take custody.

That first arrest was followed five days later by a drunken-driving arrest, then yet another DUI arrest this summer. In both those cases, ICE says he was released before their officers could encounter him.

The two murders have not sparked much soul-searching among Seattle officials.

A number of law enforcement and elected officials ignored requests for comment from The Washington Times, while King County Executive Dow Constantine released a statement after the Carillo-Lopez case in which he blasted ICE for “seeking to sow fear and division for political gain.”

“ICE is now on a public relations offensive against jurisdictions that follow the rule of law, alerting the media to instances when agents send civil immigration detainers that are prohibited by county policy,” he said in his statement.

He said if ICE obtains a warrant signed by a judge, the county would comply, but otherwise they will continue to reject requests to help facilitate deportations.

“To be clear, we do not hold people against their will in our detention facilities unless ordered to do so by a judge. We will continue to honor the Constitution, rather than the extrajudicial orders of any person, including the president,” Mr. Constantine said.

Mr. Constantine did not respond to a follow-up inquiry after the Iraheta-Lopez charges.

ICE says Mr. Constantine is intentionally misleading the public about the immigration system.

“They know full well NO such warrant exists for immigration purposes,” said Nathalie Asher, director of removal operations at ICE’s Seattle field office.

Besides, she said, King County doesn’t need a warrant to notify ICE when it’s about to release someone — yet the county refuses that step, too.

“King County’s willful refusal of ICE warrants only protects those who harm the community,” she said.