They, however, used this castle as a base for the highway robbery of passing merchants. At the beginning of the 15th century, the castle belonged to Petr of Pětichvosty who, during the war of the unity of nobelman and King Vaclav IV, remained loyal to the king. Between 1414 and 1445, the castle was owned by Beneš Libun of Dubá who fought in the noblemen’s army at Lipany and, in 1435 he was also present at the siege of Ostromeč Castle. It is likely that his son did not live at the castle and, after 1461, he sold it to his neighbour Zdeňek Konopišťský of Šternberk who annexed it to the Konopiště Estate. Zdeňek was the enemy of King Jiří of Poděbrady whose army conquered the castle in 1468. The castle is once again mentioned in 1495 and in 1500 although as being deserted and, in the course of the 16th century, its destruction was complete.
Entrance to the castle is provided by a staircase from the rear sloping-part of the promontory to the forecourt which is separated from the main keep by a moat which has been dug from the rock and fortified by ramparts and a moat which has been fortified on two accessible sides. We enter the castle through a square gate. The oblong shape of the Keep was surrounded by a wide belt of land between the walls and the moat which has been preserved best on the south western side (almost at the original height with some remnants of the battlements). At the entrance there are remnants of possibly two buildings. The oblong courtyard was protect with high walls on the long side and, on the short side, closed with two palaces. Based on this ground plan, Kožlí belongs to the type of castle with two palaces which, in our country, started to be built in the first half of the 14th century. Massive remnants of fortified walls were still standing in their original places at the begining of the 1940s however they collapsed in several places and consequently only the part above the Janocický potok remain.