It's been nearly a year since a 5-year-old boy died in a Butler County doctor's office after undergoing an unconventional treatment for his autism and authorities still are wrestling with whether the death was criminal or simply tragic.

"This has been a tough one," said District Attorney Randa Clark, who along with investigators from the Butler barracks of the Pennsylvania State Police has logged hours with medical experts, autism Web sites, and federal and state health officers in an effort to discern the right way to proceed.

Ms. Clark now is pinning her hopes for clarity on a pending review by a special body of the state attorney general's office. "I'm very pleased they have agreed to accept our case,'' Ms. Clark said of the attorney general's Medical/Legal Advisory Board on Child Abuse.

At the center of the case is Abubakar Tariq Nadama, a British boy who was brought to the United States by his mother, Marwa, specifically to receive chelation. It's a treatment that involves the administration of a liquid that pulls heavy metals from the bloodstream.

Though it is not embraced by the traditional medical community, the treatment has increased in popularity in recent years among those in autism circles who believe that the disorder is related to "metal poisoning."

Tariq, as he was known, was receiving Disodium EDTA intravenously in the Portersville office of Dr. Roy Eugene Kerry when he went into cardiac arrest, then died.

An autopsy determined the cardiac arrest was caused by a shortage of blood calcium. Dr. Mary Jean Brown of the Atlanta-based U.S. Centers for Disease Control and Prevention reviewed the autopsy and determined the chelation treatment itself would have been harmless had the child been given the correct agent.

Dr. Brown speculated there was a mix-up of medications in the doctor's office because the agents are colorless, odorless and sound alike. The agent the child was given was Disodium EDTA while the harmless agent would have been Calcium Disodium EDTA.

Other medical experts have questioned whether there was a medical mix-up or a mistake of ignorance. Doctors have told authorities that some groups supporting chelation have actually advertised Disodium EDTA as the proper agent to be used for the treatment of autism.

"There are many questions,'' Ms. Clark said.

The attorney general's advisory board will meet privately Sept. 20 in Harrisburg with the district attorney and state police investigators.

The panel is a body of about 50 experts who meet about six times annually on cases in which the evidence and its significance are inconclusive or unclear, said Barbara Petito, a spokeswoman for the attorney general's office.

"It's a fabulous resource. It would be almost impossible for an individual county to get immediate access to this range of experts," Ms. Petito said.

Members of the panel, which was created in 1988, include experts from an array of disciplines that include forensic pathology, pediatric medicine, neuroradiology, neuropathology and psychiatry, as well as district attorneys, police investigators and representatives from child protective services agencies.

Ms. Clark and Butler County Coroner William Young had initially considered holding a coroner's inquest into the death as a way of building a case. But Ms. Clark said she believes the expertise of the attorney general's panel should precede an inquest.

"At an inquest, you need medical experts lined up. When you go for an inquest, in my opinion, you're asking for a finding of criminal charges. I'm trying to figure out if I have grounds for an inquest. Do I have grounds to proceed criminally? I'm taking a cautious approach," she said.

The advisory panel reviews about 10 cases annually.

John P. Gismondi, a Pittsburgh attorney who specializes in medical malpractice and who is representing Mawra Nadama and her husband, a high-ranking doctor in Britain, said the family supports Ms. Clark's strategy.

"It's a year later and they remain in the dark and wondering what happened. Anything that sheds light on the situation is something that's useful and productive,'' Mr. Gismondi said.

He said the progress of the investigation "has been slower than they would have anticipated or liked but they are respectful of the process and they understand that these things can take time. They want to see it play out."

He said a civil lawsuit is "certainly an option that's being seriously considered" and he acknowledged that the pending criminal investigation is "influencing timing to some extent." Pennsylvania statutes allow two years for the filing of a civil claim.

Mr. Gismondi said he hopes the attorney general's advisory panel will help investigators determine why Tariq was given the wrong chelation agent. "There's no doubt he didn't get the right stuff. The question is why," he said.