Justin Bieber Arrest: Pop Star Tested Positive For Pot, Prescription Drugs

Justin Bieber Mugshot - P 2014

Justin Bieber Mugshot - P 2014

UPDATED: A toxicology report reveals what the pop star was under the influence of when he was arrested in Miami last week.

Justin Bieber tested positive for pot and prescription medication when he was arrested in Miami Beach last week, according to the toxicology report obtained by The Hollywood Reporter.

Bieber's urine was tested after his DUI bust on Jan. 23, revealing that THC and Alprazolam were in his system.

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Alprazolam is the key ingredient in Xanax, a prescription antianxiety medication.

Read the full toxicology report here.

Bieber tested negative for cocaine, opiates, meth and other drugs.

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The report is consistent with reports following Bieber's arrest in which he said that his mother had given him the prescription drugs he had taken. He also told cops he had been smoking pot prior to his arrest, according to reports.

Bieber, who is set to be arraigned Feb. 14, pled not guilty Wednesday to charges of DUI, resisting arrest and having an expired driver's license.