Bryan Vasquez was reported missing on Aug. 14. His body was found in a lagoon near his home nearly two weeks later, authorities said. The Orleans Parish Coroner's Office determined his cause of death was blunt trauma consistent with an alligator attack and drowning.
His mother, Hilda Vasquez, was taken into custody on Sunday and has been charged with negligent homicide and second-degree cruelty to juveniles, police said.
Police alleged there had been a "pattern" of negligence by the mother and that Bryan had previously been a victim of "trauma."
"There has been a pattern of both negligence and abuse over Bryan's 12 years," Deputy Superintendent Nicholas Gernon said during a press briefing on Sunday. "We believe that we can prove that that pattern of negligence and abuse led to ... undue pain and suffering on his part."
Vasquez was previously convicted of abusing Bryan when he was 3 months old, causing a skull fracture, broken legs and a collapsed lung, according to Gernon. The infant was removed from the home, then the Louisiana Department of Children & Family Services at some point returned him, he said.
The New Orleans Police Department said the case remains an "active and sensitive investigation."
"Our detectives will continue to pursue every fact and every aspect and to any investigative leads," Assistant Superintendent Hans Ganthier said during the briefing. "Out of respect for the ongoing process, a lot of the details cannot be released."
The Orleans Parish District Attorney's Office will review the case and make any charging decision, Gernon said.
"This was an emotional and really traumatic case, not just for the community, the family but also our own officers," Ganthier said. "We wish the outcome would have been different, but it's not the case so we have to pursue and seek justice for Bryan."
Vasquez is in custody at the Orleans Parish jail. It is unclear if she has an attorney at this time.
Bryan, who was nonverbal and had a neurodevelopmental condition, was last seen the morning of Aug. 14 on a street in New Orleans wearing an adult diaper, police said. Members of the United Cajun Navy located his body in a lagoon near his home on Aug. 26 with the help of thermal drone technology. The coroner was unable to confirm the timing of the child's death, police said.
Following the discovery of his body, New Orleans Police Department Superintendent Anne Kirkpatrick told reporters there had been "history" with the family that preceded his death and former allegations involving the family but did not go into detail at the time, saying it was a "matter of court record."
Police had seized phones from the victim's family, according to Kirkpatrick, who said it was not an unusual step to take "in order to look at everything."
Police have launched an internal investigation into a five-hour delay in their initial response to the 911 call reporting him missing, Kirkpatrick said.
"There could be reasons to explain a five-hour delay, but on its face it's inordinate," she said at a press briefing on Aug. 27.
The police department also requested wildlife officials to eradicate alligators in the body of water where Bryan was found.