On April 9 KST, Trubaum Research Center revealed the results of an 'Author Identification Assessment' conducted with text messages allegedly exchanged between actor Kim Soo Hyun and the late actress Kim Sae Ron in 2016, comparing them to text messages sent by Kim Soo Hyun to his acquaintances in 2025. Kim Soo Hyun's side directly requested the assessment from Trubaum and provided the text data from 2025. 

Reportedly, an 'Author Identification Assessment' statistically evaluates whether documents written at different points in time were composed by the same individual. The method quantitatively measures the number of times that certain parts of speech appear in each document, calculating their average usage across 18 linguistic features. By identifying an individual's linguistic pattern, the assessment determines the probability that written messages may have been composed by the same author. 

Trubaum found that there were "no statistically significant differences" among messages exchanged between Kim Soo Hyun and Kim Sae Ron in 2018 and sample messages provided by Kim Soo Hyun's side, actual messages exchanged between him and acquaintances in 2025. The probability that the messages were written by the same individual (Kim Soo Hyun) was 92%. 

However, the research firm did find "statistically significant differences" in linguistic patterns when comparing the messages from 2016 with the messages from 2025. The assessment reportedly indicated a "high probability" (95%) that the messages from 2016 were not written by Kim Soo Hyun.

Meanwhile, HOVERLAB previously publicized recreated text messages exchanged between Kim Soo Hyun and Kim Sae Ron to prove that the two stars dated in 2016, when Kim Sae Ron was still a minor. However, some questioned the "reliability" of the recreated text messages, prompting Kim Soo Hyun's side to hire a private firm specializing in court evidence assessment to question their validity. 

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