The new prisoners had to construct the camp themselves, beginning with the barbed wire fence; this was initially the main use of forced labor. While performing this heavy and dangerous work, the prisoners lived in makeshift structures. Simultaneously, hundreds of prisoners had to work in the quarries. The camp's population had increased to 1,500 following arrivals from Dachau, Sachsenhausen, and Buchenwald. In January 1939, the first commandant, Jakob Weiseborn, unexpectedly died. He was replaced by a former SS officer at Dachau, Karl Künstler, who presided over an era in which the camp became an economically productive center for granite quarrying, and increasingly deadly for its prisoners. With the first barracks complete, in 1939 work began on an internal jail, guard towers, a washing facility, and a sewer system. In April 1939, the economic productivity of the camp led to Pohl ordering the camp to be expanded to fit 3,000 prisoners. To build additional barracks, terraces had to be cut into the hillsides, an arduous task that led to many injuries.