Prince was unconscious when his bodyguard carried him down the steps of his private jet after it made an emergency landing in Moline, Ill., just days before the superstar collapsed and died at Paisley Park in Chanhassen.

That, combined with the discovery of prescription pills at the death scene, kept drugs as a focus in the investigation into how Prince died.

During the middle-of-the-night stop on the taxiway of the Quad City International Airport, paramedics from the local fire department, responding to a call of an “unresponsive passenger” on Prince’s flight, worked to revive Prince before speeding him to the hospital, according to fire and ambulance records released Wednesday by the city of Moline.

The heavily redacted document shows that emergency responders arrived at 1:24 a.m. on April 15 and cleared the scene by 2:16 a.m. The records contain almost no detail about what the responders did.

Several sources with direct knowledge of the death investigation, however, have told the Star Tribune that paramedics gave Prince a shot of the opioid antidote Narcan, and that Prince had overdosed on an opioid.

Prince’s plane was en route to Minneapolis from Atlanta — where he had played two concerts in one night — when it made the emergency landing.

The records listed paramedic Justin Frederiksen as a secondary caregiver. Reached by phone Wednesday, Frederiksen said he had “no comment on it.”

Paramedic Austin Rands, listed as the primary caregiver, did not return calls for comment.

Controllers initially were confused about the nature of the emergency beyond the fact that there was an “unresponsive passenger” on board, according to the 7-minute air traffic control recording of the emergency landing. The pilot then clarified that the passenger was a man, but did not identify him.

Prince’s body was found six days later at Paisley Park. Sources have told the Star Tribune that they are investigating the role opioids may have played in his death. Prescription pills were found on the scene, but sources said it was unclear whether they were prescribed to Prince. Authorities have said that Prince was alone when he died and that neither foul play nor suicide is suspected.

Prince’s body was cremated last week and a private service was held Saturday at Paisley Park.

The Carver County Sheriff’s Office has said that a cause of death probably won’t be made public for weeks, until it receives reports from the medical examiner and toxicology results.

The timetable for the results of Prince’s autopsy remains unclear, said Martha Weaver, a spokeswoman for the Midwest Medical Examiner’s Office, which conducts cause-of-death investigations for 19 Minnesota counties, including Carver. However, this type of investigation typically lasts four to six weeks because of the way testing is sequenced in order to determine a cause.

That is especially true when drugs are suspected. Initial screening can rapidly determine the presence of alcohol, opioids, or other classes of drugs, but it doesn’t indicate the precise medication, the dose, and whether the amount of any one drug or combination of drugs was toxic enough to have contributed to the death.

“What might be toxic for somebody who doesn’t take pain medication might be the standard operating level … for someone who is on long-term pain medication,” said Mike Burakowski, supervisor of investigations for the Hennepin County medical examiner’s office, which isn’t involved in the Prince case.

The next step is “quantification,” which involves more sophisticated toxicology tests to identify the exact drugs taken, microscopic analysis of brain, heart or other tissue samples to assess any drug-related damage, and a re-analysis of death scene findings such as the number of pills left in a prescription pill bottle, he said.

The absence of positive drug findings in a suspected overdose case also could lead to testing for rare or synthetic drugs that aren’t identified by traditional toxicology methods.

Consultation from a neurology expert also is common when investigating deaths of people with prior histories of brain disorders such as epilepsy, and can affect the timing of results, Burakowski said.