(CNN) — A Hawaii couple charged with the murder of their adopted 6-year-old daughter was indicted by a grand jury and faces additional charges in her death, authorities said.

Lehua Kalua, 44, and Isaac “Sonny” Kalua, 52, each were indicted and charged with one count of second-degree murder, one count of first-degree hindering prosecution, two counts of persistent nonsupport and two second-degree counts of endangering the welfare of a minor, according to Prosecuting Attorney of Honolulu Steve Alm.

Lehua Kalua was additionally indicted and charged with two counts of abuse of family or household members.

The couple reported Isabella “Ariel” Kalua missing on September 13, but investigators believe the girl was killed about a month earlier, with her last appearance on home video surveillance systems occurring on August 18.

Conviction of second-degree murder carries a mandatory life in prison with the possibility of parole, according to the news release from Alm’s office.

“But if convicted, Lehua and Isaac Kalua face an extended term of imprisonment of life without the possibility of parole because Ariel was under the age of 9 when she was allegedly murdered,” the office said in the release.

Last week, the couple pleaded not guilty through an attorney. CNN contacted attorneys for Isaac and Lehua Kalua and both declined to comment.

“The allegations in this case are heinous beyond description,” Alm said in a written statement. “And we will hold Lehua and Isaac Kalua accountable for their alleged crimes against this defenseless child.”

Police investigating horrific conditions

Ariel and several of her siblings were adopted or are being fostered by the Kaluas, according to the documents, which were obtained by CNN affiliate Hawaii News Now.

An affidavit in support of an arrest warrant for Lehua Kalua filed recently in Family Court of the First Circuit in Hawaii describes the gruesome conditions police are investigating.

In early November during an interview with police, one of Ariel’s siblings told authorities that Lehua Kalua bought a dog cage on the internet to lock Ariel at night because the 6-year-old “would sneak around at night and want to eat because she was hungry,” the document says. The child told police Ariel was often denied food by Lehua Kalua, adding they did not have a dog at the time.

The child told police they were “asked to keep a secret by Lehua and Isaac regarding what happened to [Ariel],” court documents say.

The sibling said Ariel “was in the bathroom in a dog cage, duct tape on her mouth and nose, and she didn’t wake up,” the documents allege.

The sibling also told police that Ariel was not breathing, and Lehua Kalua put her in the bathtub to try to wake her up. The sibling described to police helping to carry their sister into their shared bedroom.

The police were told the child didn’t know what happened to Ariel after that, the affidavit says. Police have said her remains have not been found.

(Copyright (c) 2021 CNN. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

Join our Newsletter for the latest news right to your inbox