TAMPA -- A 14-year-old boy who was roughed up by guards at a Panama City juvenile boot camp in a videotaped altercation died because the sheriff's officials suffocated him, Hillsborough County's medical examiner said Friday.

The findings of Dr. Vernard Adams's autopsy on Martin Lee Anderson conflict with the results of the initial one by Dr. Charles Siebert, the medical examiner for Bay County. He ruled the boy died had a natural death from complications of sickle cell trait, a usually benign blood disorder many blacks have.

``Martin Anderson's death was caused by suffocation due to actions of the guards at the boot camp,'' Adams wrote in a statement. He said the suffocation was caused by hands blocking the boy's mouth, as well as the ``forced inhalation of ammonia fumes'' that caused his vocal cords to spasm, blocking his upper airway.

The new findings were announced as part of an investigation by Hillsborough County State Attorney Mark Ober. Gov. Jeb Bush appointed him in February to investigate the death after Siebert's findings were disputed by the 14-year-old boy's family and others. Ober asked Adams to do a second autopsy.

No one has been arrested and Ober said no timeline has been established for completing the investigation.

``I assure the family of Martin Anderson and the people of the state of Florida that my office is working diligently to aggressively investigate all aspects of this case,'' Ober said in a statement. He declined to answer questions about Adams' findings.

Anderson's parents, Gina Jones and Robert Anderson, planned a news conference Friday evening at their attorney's Tallahassee office to respond to the findings. Marc Tochterman, a spokesman for the Bay County Sheriff's Office, which operated the boot camp, said the agency had no immediate comment.

Siebert did not immediately return a call seeking comment, but he has repeatedly stood by his findings, saying they were based on reliable science, not emotions. He also has said he was being unfairly attacked by special interest groups.

``I am disturbed by Dr. Adams findings and consider the actions of the Bay County boot camp guards deplorable,'' Bush said in a statement. ``I assure Gina Jones and Robert Anderson that the state remains committed to providing any resources State Attorney Ober deems necessary to complete this investigation as quickly as possible.''

Attorney General Charlie Crist said Friday that Siebert ``should probably be suspended pending further review.'' He said the second autopsy report wasn't surprising.

``I can't say I'm shocked after having watched the tape. What was surprising was the first autopsy,'' Crist said. He said there ``probably will be arrests.''

Waylon Graham, attorney for sheriff's Lt. Charles Helms, who was second in command of the boot camp and present in the exercise yard that day, said he wasn't shocked by Adams' report. Graham said the investigation has turned into a ``witch hunt'' with criminal charges inevitable.

``I think (Helms) knows what's coming next,'' Graham said. ``When you get an autopsy with results like that it's pretty clear that they are going to charge him and obviously the others. It would take a pretty naive person to think otherwise.''

He said Helms doesn't believe that the guards caused Anderson's death.

Anderson was kneed, struck and dragged by guards on his first day at the boot camp for juvenile offenders. He was eventually was taken to a Pensacola hospital where he died the next day, Jan. 6. The ordeal with guards was captured by a camp security camera and later broadcast nationally.

Anderson had collapsed while doing push-ups, sit-ups, running laps and other exercises that were part of his admission to the camp. The sheriff's office said force was used on Anderson because he was uncooperative.

Adams found the repeated blows to Anderson's limbs ``left several bruises but did not contribute to his death.'' ``In other words, he was not beaten to death,'' Adams wrote in the statement.

Siebert found that the exertion from that exercise triggered the sickle cell trait and ultimately caused small blood clots to develop in the bloodstream, which resulted in internal bleeding.

His body was exhumed in Panama City and brought to Tampa in March for the second autopsy. It was observed by forensic pathologist Dr. Michael Baden, who said afterward that he believed Anderson didn't die from sickle cell trait or any other natural causes. Baden was hired by the boy's family.

The death also sparked protests at the state Capitol, forced lawmakers to scrap the military-style camps and led to the resignation of the state's top law enforcement officer, who started the boot camp in Panama City when he was Bay County sheriff. Bush said Florida Department of Law Enforcement chief Guy Tunnell shouldn't have sent e-mails to the current sheriff questioning those who criticized the boot camp concept.

Anderson has entered the camp for a probation violation for trespassing at a school after he and his cousins were originally charged with stealing their grandmother's car from a church parking lot.

Associated Press writers Melissa Nelson in Pensacola and Andrea Fanta in Tallahassee contributed to this report.