Photo taken by a cellphone on March 26, 2015 shows Andreas Lubitz's home, the co-pilot who was charged of deliberately crashing Germanwings A320 flight, in Montabaur, western Germany. German police are keeping the Germanwings' co-pilot's home in the town of Montabaur, about 100 km northwest of Frankfurt, under surveillance. (Xinhua/Shen Zhengning)

Photo taken by a cellphone on March 26, 2015 shows media workers gathering near Andreas Lubitz's home, the co-pilot who was charged of deliberately crashing Germanwings A320 flight, in Montabaur, western Germany. German police are keeping the Germanwings' co-pilot's home in the town of Montabaur, about 100 km northwest of Frankfurt, under surveillance. (Xinhua/Shen Zhengning)

Photo taken by a cellphone on March 26, 2015 shows investigators entering Andreas Lubitz's home, the co-pilot who was charged of deliberately crashing Germanwings A320 flight, in Montabaur, western Germany. German police are keeping the Germanwings' co-pilot's home in the town of Montabaur, about 100 km northwest of Frankfurt, under surveillance. (Xinhua/Shen Zhengning)

An investigator enters Andreas Lubitz's home, the co-pilot of the fatal Germanwings A320 flight who appeared to have deliberately crashed the plane, in Montabaur, western Germany. German police are keeping the Germanwings' co-pilot's home in the town of Montabaur, about 100 km northwest of Frankfurt, under surveillance. (Xinhua/Luo Huanhuan)

Investigators search Andreas Lubitz's home, the co-pilot of the fatal Germanwings A320 flight who appeared to have deliberately crashed the plane, in Montabaur, western Germany. German police are keeping the Germanwings' co-pilot's home in the town of Montabaur, about 100 km northwest of Frankfurt, under surveillance. (Xinhua/Luo Huanhuan)

Investigators enter Andreas Lubitz's home, the co-pilot of the fatal Germanwings A320 flight who appeared to have deliberately crashed the plane, in Montabaur, western Germany. German police are keeping the Germanwings' co-pilot's home in the town of Montabaur, about 100 km northwest of Frankfurt, under surveillance. (Xinhua/Luo Huanhuan)