Apparently, Thomas Schneider manipulates the results of his experiments. Robert informed him that he would report this to the organization www.breakthroughprize.org where Thomas is applying for a grant. This is about 3 million dollars, which is a serious motive for a murder.
The Anduran ampoule can be seen in the refrigerator in one of the evidence images. Thomas was sure that nobody could enter his room, (that’s what it says in Robert’s email) but stupidly the stolen medicine can be seen on the photo he sent to the magazine for publication. This last piece of evidence shows that Thomas is most likely to be the murderer.

How did he plan the whole thing?

Thomas was Martin’s roommate; he most likely knew about Martin’s drug addiction and where Martin hid the syringe. When Martin was asleep, he stole the syringe with Martin’s fingerprints and traces of morphine. He pretended to be in the shower and then carried out his plan to turn off the lights and commit the murder. Then he returned and planted the evidence of the murder on Martin.
We would like to remind you that we do not make the final decision about who the murderer is, but only help the police to find a potential suspect. The final decision will be made by the court.

But we are certain of this… Thomas is the murderer.