Bryan Kohberger flipped out on a hotel clerk who he thought overcharged him after he booked a room on a travel website … just months before the Idaho murders … this according to a newly released police report.

According to cops, the now-convicted serial killer showed up alone at the hotel in Pullman, Washington, on June 30, 2022, after he booked the room through Expedia.

The docs say Kohberger made a beeline for the front desk — where the female employee was apparently training that day — and apparently got mad when he thought she overcharged him for the room while checking him in.

Cops say they were told Kohberger became “really upset” over being double-charged, but once she fixed the mistake, he was “nice” and even began flirting with her.

After their chilling chat, Kohberger left the hotel … and several months later went on to butcher 4 University of Idaho students at an off-campus house in Moscow, Idaho, in November 2022.

Kohberger fatally stabbed Ethan Chapin, 20, Kaylee Goncalves, 21, Xana Kernodle, 20, and Madison Mogen, 21. He pled guilty to the 4 murders as part of a deal that landed him in prison for the rest of his life without parole, avoiding the death penalty.