Probably not that long time before the arrest, as that would only take 3-5 min to get a clear picture. However, it´s nothing strange they will be looking. That will be a big part of the work, as they have to look at and consider all the evidence in a criminal case. Totally normal if you ask me.
On the other hand, maybe the police in the country you come from doesn´t look at the evidence. Just, because they do not want same comment you give to the Thai police when they are just doing regular police work, right?