In a recent post on his personal account, the older brother of the late singer and actress Sulli (Choi's brother) announced that he possesses a 37-minute recording containing conversations with his younger sister's former manager.
The recording is said to mention IU, Kim Soo Hyun, Lee Ro Bae (Kim Soo Hyun's cousin), treatment at a mental hospital, SM Entertainment company and aspects of Sulli's private life at that time.
Choi also said: "I have many things to ask, but I am trying to restrain myself because I think of my mother. Last year I only briefly mentioned the movie, but I have no intention of continuing to take advantage of this.
At the same time, he emphasized: "I want to make it clear in advance that nothing is false.
Previously, on May 21, Sulli's brother posted: "The moment you try to come back, the second round will begin. The choice is yours", and revealed that the person he mentioned is "a person from the stars" - referring to the movie "My Love from the Star" starring Kim Soo Hyun.
This statement is seen as a warning related to Kim Soo Hyun's public activities and the possibility of returning to the entertainment industry, in the context that the police have just announced the results of the investigation into the incident between Kim Soo Hyun and the late actress Kim Sae Ron.

Gangnam Police Station (Seoul) in the arrest warrant application sent to the Procuracy for Kim Se Ui - representative of the YouTube channel Garosero Research Institute - clearly stated: "The suspect, although knowing clearly that actor Kim Soo Hyun did not date the deceased (Kim Sae Ron) when she was a minor, and her death was not related to the actor, still spread false information with the aim of defaming her".
Police also believe that KakaoTalk conversations between the two people, along with audio recordings believed to be of Kim Sae Ron publicly released by Kim Se Eui, have all been forged.
Meanwhile, in March last year, Sulli's brother once questioned whether his sister was forced to film 18+ scenes and nude scenes when participating in the movie "Real" released in 2017.
This film is invested and directed by Lee Ro Bae - known as Kim Soo Hyun's cousin. Kim Soo Hyun is the main actor of the film.
Sulli's brother said that "IU is close to Kim Soo Hyun" and revealed that she "rejected the female lead role initially in Real, then gave the script to Sulli".
Regarding this issue, Kim Soo Hyun's management company once made an official statement, stating: "The late artist Sulli was informed in advance and clearly understood the content of the scenes before participating in filming".
Regarding the suspicion that although there are stunt actors, Sulli is still forced to film hot scenes, the company explained: On the "Real" film set, there are no stunt actors, only stunt actors.
This person does not replace the main actor in hot or dangerous scenes, but only plays the role of imitating the actor's movements to provide technical support during filming preparation.