The intense heat they were having at the time of her murder led the ink on the paper in her pocket to transfer partially to the inside of her pants pocket, and Abby was able to determine that she had a list of shipping tracking codes for an online pharmacy in her pocket at the time she was murdered.
When Abby looks into it, she realizes that Mae was probably moved so that the killer could get something out of her pocket.
Once the team starts to investigate Mae’s case, using the files brought over from the Virginia State Police, they see that she was turned over after her death.
It turns out that Mae, who had been a military investigator herself at one point, had accidentally gotten wind of a ring of prescription drug thefts and got too close to the truth and was killed for it.