The starting point of the Moon Se-gwang conspiracy theory is an interview with a former forensics chief, but it's quite nonsense

The forensics chief, Lee Keun-woo, passed away in 1999. Back in 1989, when he was 67, he claimed in the monthly magazine 'Dari' that Yuk Young-soo was not shot by Moon Se-gwang. That claim was subsequently cited by programs like 'Unanswered Questions' (Geu-al) and outlets like Pressian, leading to the 'assassin(s)' theory.
However, this interview should not be taken at face value, as it is not an official investigation record. Of course, conspiracy theorists might believe that the official investigation records were fabricated and that this man's words are the truth.
But even looking at it now, it is obvious that this man was lying. For example, regarding the vehicle Moon Se-gwang arrived in.
“Chief Lee discovered another suspicion during the crime scene investigation. The fact was that the luxury sedan Moon Se-gwang arrived in was a vehicle with a fake license plate.
The black sedan, 'Seoul 2-Ba 1091', which Moon Se-gwang arrived in, was a Ford 20M, a luxury car that an ordinary citizen could not even dream of owning.
Chief Lee called the vehicle registration office to ask who owned this vehicle.
However, the registration office replied, 'That license plate number is not registered.' Chief Lee repeatedly inquired, saying, 'What? If that license plate is not registered, then... does that mean it's a fake plate? Please check again,' but the result was the same.
Based on this, Chief Lee reached the conclusion that there was an 'accomplice' of Moon Se-gwang within the country. However, five days later on August 21, the investigation headquarters announced that Moon Se-gwang acted alone, stating, 'We investigated about 70 people, including Moon Se-gwang's relatives, but found no evidence of a domestic accomplice.'”
This forensics chief claimed that the Ford vehicle Moon Se-gwang arrived in at the crime scene (Seoul 2-Ba 1091) had a fake license plate and that there was an accomplice.
The problem is, the owner of this vehicle was identified immediately. lol. According to reports by the Dong-A Ilbo two days after the incident, the owner of the car was Kim Sa-bok, a luxury call-taxi driver—the very same person who served as the motif for the famous movie 'A Taxi Driver' related to the 5.18 Gwangju Uprising. hahaha. At the time, Kim Sa-bok operated a luxury call-taxi service near the hotel area, but during the Moon Se-gwang incident, he wasn't the one driving; his assistant, Mr. Hwang Su-dong, drove the 1091 vehicle to pick up Moon Se-gwang from the Chosun Hotel and take him to the crime scene.
The story that KCIA agents investigated Kim Sa-bok and released him because no suspicious activity was found is a somewhat famous story that comes up in interviews with former KCIA officials now that Kim Sa-bok has become famous through the movie 'A Taxi Driver.'
Yet, this forensics chief is talking nonsense, claiming that because he couldn't find the owner of the 1091 car, Moon Se-gwang must have had an accomplice! hahaha. Kim Sa-bok was Moon Se-gwang's accomplice? That would be quite a massive claim! lol. Meanwhile, former KCIA officials recall that there were no suspicious points. hahaha
Anyway, even an ordinary civilian like me can see these flaws just by reading the interview, so it's hard to blindly trust the conspiracy theory claimed by the forensics chief. If we want to be technical, it might be because there was information not passed from the investigation headquarters to the forensics chief, but it is also a reason why it is difficult to take the forensics chief's recollections at face value.