This takes place during the case Robber From the Darkness - Part 6
Commander Denulth played a small role in one of Meg's cases, reguarding Major Mary Rancour's disappearance as a teaser to Kindred Spirits. Talking to him revealed that he was not there for her abduction, as he was fighting trolls, presumably on the front lines. He does assure the player that had he been there, he would've made sure it didn't happen.
The following takes place during the case Jewel Thief
Another case in Mega May involved a thief who stole from Herquin's Gems. You learn that the suspect is an Imperial Guard with a limp. When Denulth learns of this information, he is generally disgusted, as he recognises who it is. In addition, he gives the player full permission to search the suspect's footlocker, and promises that he will be reprimanded accordingly.