The Action T4 Euthanasia Centres had temporary holding stations for victims. For example, many trucks carrying victims to Hartheim would stop at the Niedernhart Mental Institute in Linz, where Rudolf Lonauer was the senior doctor, as he was at Hartheim. At Niedernhart, victims were mainly killed by starvation or medical overdose (by giving deadly amounts of medicine). Patients would be put into categories. Some would be chosen and taken to Hartheim to be killed.