UPDATED 4:15 p.m ET: The cause of Juice WRLD's death is reportedly still unknown following his autopsy on Monday. The Cook County Medical Examiner's Office released a statement following the procedure, indicating that "additional studies are required to establish the cause and manner of death." Cardiac pathology, neuropathology, toxicology, and histology could be conducted to determine the cause of death.

Additionally, the Chicago Tribune reports that authorities were already at the airport waiting for Juice and his entourage to arrive as it was suspected the private jet was transporting contraband. FBI agents and police officers were at the scene, and the rapper "began convlusing [and] going into a seizure" as the luggage was searched. He was briefly revived but sources say when he woke he was "incoherent" after he was administered an anti-overdose medication.

Sources claim that authorities asked Juice's girlfriend at the scene if he had any pre-existing medical conditions, to which she replied that he "takes Perocet and has a drug problem." 

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Authorities confiscated 70 pounds of marijuana following Juice WRLD's sudden death after a seizure on Sunday. As TMZ reports, the Death Race for Love rapper flew into Chicago's Midway airport via private jet. After he was rushed to hospital, the FBI confiscated the weed from several suitcases. Sources close to the situation also alleged that Juice WRLD—born Jarad Anthony Higgins—took "several unknown pills" prior to his seizure.

Associates of the rapper have claimed that he has a Percocet problem, while law enforcement reportedly discovered a bottle of codeine on the plane. His cause of death has yet to be determined, although the Cook County Medical Examiner will perform an autopsy on Monday. Word broke on Monday that two of his security guards, who were present at the time of his death, were arrested at Midway airport after it was discovered they were carrying three guns, metal-piercing rounds, and a high-capacity magazine between them.

Shortly before his death, Juice WRLD appeared to be in high spirits in videos from the plane. Another source said that he was expected to attend his own 21st birthday party the night he arrived in Chicago, Fox 32 Chicago reports. He was returning home to Chicago from California when he suffered the seizure. The rapper was pronounced dead minutes after he was rushed to the hospital. Juice WRLD had just turned 21.

Since news broke of his death, Juice WRLD's breakthrough track "Lucid Dreams" has topped both the Apple Music and Spotify U.S. streaming charts. A good number of his other tracks have seen an increase in plays, too, including "Bandit," "All Girls Are the Same," "Legends," and "Robbery."