I'd like to confirm if the 後に in
is referring to sometime later. In other words, if the sentence can be translated as
When the researchers followed later on, the Professor showed a smile on its face.
Additionally, what is the function of に in this case? I don't think it's a temporal marker since relative time expressions (e.g. 明日, 今日...) do not take に. My guess is that 後に is an adverb modifying 続く, but I'd like to check.
Finally, this was taken from a Pokemon light novel. For context, a group of researchers has found a lithograph inside some ruins and are discussing the engraving. With this in mind, I'm also wondering if this 続く could refer to their talk instead.
I've included the excerpt below: