Taos County District Attorney Donald Gallegos said his office will now seek grand jury indictments involving the death.
He said seeking indictments will allow more time to gather and analyze evidence, and enable his office to avoid calling juveniles from the compound as witnesses in court.
Three of the adults from the compound had been released Wednesday after state judges dismissed child neglect charges, noting that prosecutors missed deadlines to present evidence and that charges may have been improperly filed by the sheriff and prosecutors.
Deadlines loomed in state court next week to show evidence backing up charges of child abuse resulting in death against Jany Leveille and Siraj Ibn Wahhaj, the father of the boy whose body was found in an underground tunnel at the compound near the Colorado border.
Those charges were subsequently dropped Friday in lieu of taking the case to a grand jury set to convene in late September.
"Going to a grand jury allows us to get that information and vet it and not be under the 10-day window, which is quite burdensome," Gallegos said, describing state rules on due process for jailed defendants that require a quick showing of probable cause that a crime was committed.
All five people arrested by the FBI will remain in custody pending a Tuesday hearing in federal court.
Joe Shattuck, an Arizona-based criminal defense attorney who has practices in New Mexico, described the firearms possession and conspiracy as "low hanging fruit" that keeps all five defendants behind bars.
"The feds are looking to get their thumbs into the pie — they may want to get deeper into the case later," said Shattuck, who is not involved in the case.
The U.S. Attorney's Office in Albuquerque said Leveille has been charged with being an alien unlawfully in possession of firearms and ammunition.
The other four people are charged with conspiring with Leveille. They include Lucas Morton; his wife, Subhannah Wahhaj; and her sister Hujrah Wahhaj
Federal immigration authorities have accused Leveille, a native of Haiti, of residing illegally in the U.S. for 20 years after overstaying a visitor's visa, though she was authorized to work in the U.S. from April 2017 through April 2018.
In federal court filings on Friday, the FBI said handguns, rifles and a shotgun found at the compound were purchased by Siraj Ibn Wahhaj and Hujrah Wahhaj, while one rifle had no purchaser information.
Some firearms were transported in a vehicle registered to Leveille during a portion of the family's journey from Georgia to New Mexico in late 2017, and guns were later stored under Leveille's bed. An unnamed child at the compound saw Leveille train with a gun once and fire it, the FBI said.
Kelly Golightley, a defense attorney for Leveille, said she was unfamiliar with the new charges and could not immediately comment.
"I need to investigate my cases more thoroughly to determine if charges were properly filed," she said.
Eleven children were taken into state custody in an Aug. 3 raid on the squalid compound, where a half-submerged camper was surrounded by walls of used tires and adobe walls topped with broken glass.
Sheriff Jerry Hogrefe said the property was under surveillance since May, and that he launched the raid based on an intercepted message that children were starving. A district court judge says authorities have failed to provide evidence that the children were physically neglected.
Authorities say that Abdul-ghani, the deceased boy found at the property, initially was reported missing by his mother last year from Jonesboro, Georgia, after Siraj Ibn Wahhaj said he was taking the child to a park and didn't return.
Forensic medical investigators have not yet identified the cause and manner of the boy's death.
Law enforcement officials previously accused Wahhaj and Leveille of denying the boy proper medicine and health care before he died in December 2017 during a religious ritual aimed at casting out demonic spirits.
In filings in federal court on Friday, an FBI agent reiterated accusations drawn from accounts by children at the compound that Leveille expected Abdul-ghani to be resurrected as Jesus and provide instruction to "get rid of" corrupt institutions that involve teachers, law enforcement and banks.