Family and friends of Port Adelaide footballer John McCarthy may have to wait several weeks to find out what led to his death, Las Vegas police say.

Twenty-two-year-old McCarthy was found in the driveway of the Flamingo Hotel about 5.40am on Sunday (Las Vegas time).

Medical personnel transported him to a medical trauma centre where he was later pronounced dead, Las Vegas police said in a statement.

Detectives from the Violent Crimes Section of the Las Vegas police department are conducting an investigation.

Police in Las Vegas said the cause and manner of death would be released by the Clark County Coroner’s Office.

But an officer from the Las Vegas police department told 3AW it could be weeks before the cause of death is known.

“The cause and manner of death will be released only after results of an autopsy and toxicology reports are released,” the officer said.

“It could be several weeks before a definite cause of death is known.”

Las Vegas police have appealed for witnesses who may have information about the incident to come forward.