WEST AUGUSTINE, Fla. -- After the St. Johns County sheriff tried to put to rest reports that his deputies did anything that caused the death of a suspect in custody early Tuesday, Channel 4 obtained a copy of the preliminary coroner's report that contains a fact that Sheriff Neil Perry didn't mention.

Lewis King, 39, died shortly after he was hit with two blasts of a Taser gun as, deputies said, he continued to resist following his capture following a brief chase.

Now, Perry has asked the U.S. Attorney's Office to assist in the investigation "before someone else jumps up and starts screaming they want a civil rights review."

Steve Cole at the U.S. attorney's office said the FBI and civil rights division at the Department of Justice would conduct a preliminary inquiry into the case. Based on that report, the U.S. attorney's office will decide on the next step.

Perry said such a review would be fine. "I'm glad to do that. I don't think there's any reason not to do that," he continued.

A statement from medical examiner Terrence Steiner does confirm that injury from a Taser gun "was not felt to have contributed directly to his death." Instead, a preliminary autopsy found that King likely suffered heart failure.

"The deceased had evidence of severe heart disease with a massively enlarged heart," Steiner wrote.

But the report goes on to say something the sheriff did not mention -- that King may have been asphyxiated while he was restrained.

The medical examiner called it "positional asphyxia," meaning he was in a position that did not allow his body to get enough oxygen.

"When we take action that results in either us getting hurt or someone else getting hurt, questions ought to be asked," said Perry.

The medical examiner declined a request for an interview to elaborate on his one-paragraph statement.

Asked why he didn't mention at his Wednesday news conference the possibility that King died of asphyxiation, Perry told Channel 4 he did not want to "muddy the water" about the medical examiner's investigation. He said Lewis was not hog-tied and no deputy got on top of him while he was being restrained.

King's family and friends were not satisfied with the sheriff's explanation Wednesday and called for further investigation. The family has retained the services of the Willie Gary Law Firm to represent them in the ongoing investigation into King's death.