Mardeyev was last seen in Tulsa, Oklahoma on November 29, 2011. He left his Grove, Oklahoma home alone and in a hurry at 8:00 p.m., driving his dark blue 2010 Hyundai Santa Fe with the Oklahoma license plate number 51312C, and drove to Tulsa. His car was parked in front of the Riverspirit Casino for an hour, then it left and was parked again at the Batman Convenience Store in the 1400 block of north Mingo Road. He has never been heard from again. On December 9, his car was towed from the convenience store parking lot where it had been abandoned.

Mardeyev's keys, GPS system and expensive sunglasses were inside the car, along with a bottle of Coke and an open bottle of whiskey. His Bible, which he took everywhere and which was engraved with his name, was missing. So was the paperwork he was filling out for his visa. There was gravel in the front and back seats of the car, which is uncharacteristic of Mardeyev; he kept his vehicle very clean. The car's money change compartment had been cleaned out and the radio was tuned to a rap station; Mardeyev listed only to CDs or a Russian-language station.

Because the casino has no surveillance tapes, authorities aren't sure whether he actually visited there on the day of his disappearance. According to the GPS, whoever was driving it drove from Grove to Tulsa without stopping and didn't take Mardeyev's usual route. He usually took the turnpike to Tulsa, but on the day he disappeared his car turned around at the turnpike toll gates and took another, roundabout route to Tulsa. His cellular phone was used to access the internet at 11:00 p.m. the night he disappeared, but has been turned off ever since. He was carrying his wallet, passport and approximately $3,000 to $5,000 in cash at the time he went missing.

Mardeyev was born in the Central Asian nation of Kazakhstan and was in the United States on a work visa in 2011. He lived with his sister and brother-in-law. According to them, Mardeyev was acting differently on the day of his disappearance; he seemed depressed and agitated. His mother had died in Russia and his father died in Oklahoma not long before his disappearance, and he was distraught. Mardeyev was due to fly to Russia for Christmas, but never made his flight. He and his fiancee were supposed to marry in Russia in February and then settle in Oklahoma, and he had been house-hunting in Tulsa. His family said he kept to himself and had no friends in the USA, but he was using the alias name Ratmir Maruna. Under this name he had befriended a woman and they spoke on the phone. He was considering going to meet her in person, something his relatives advised against because of his engagement.

Mardeyev hasn't been in touch with his fiancee or any of his relatives either overseas or in the U.S., and there's no evidence that he left the country after he vanished. His passport has been flagged so if anyone tries to use it to travel, the authorities will be notified. The circumstances of Mardeyev's disappearance are unclear; his case remains unsolved.