Other than that the only thing Dai Ya knew was that it was guarded securely even from the royal family members themselves. The only way to see it was to exhibit a certain level of aptitude for cultivation. Not every Han clan member was able to cultivate it.
She did try to dig further into potential suspects, but the means and reach of the Mulberry Sect were limited, and whoever the killer was, they were capable enough to slaughter the entire Han family which by itself had enough power to overturn the Mulberry Sect.
This fact slowed down her progress as she had to be careful with it and there was also the fact that her investigation into the Frozen Serenity Scripture opened her eyes to just how many powerful organizations out there had ties to it. Over the past decade, she had even given up on trying to dig further, and it was only when Xia Ting made her way to the doorsteps of her sect did she talk about the matter for the first time in so long.