It was the last weekend before the start of the new term. Many students were still lying in bed when the power of the state marched up to this quiet corner of Kiel, not far from the university: The local police, the state police from Schleswig Holstein and federal police. For the rest of the day the Edo Osterloh House on Steenbeker Strasse found itself in a state of emergency.

This is where Youssef Mohamed E. lived. Investigators believe the 22-year-old Lebanese man is one of the two bombers who tried to carry out attacks on two regional trains from Cologne to Koblenz and Hamm on July 31 using bombs hidden in luggage. The bombs were assembled in a fiendishly simple way, to be detonated using two green electric alarm clocks.

The students, who had spent the previous evening either celebrating at the back to school BBQ party or preparing for their first exams late into the night, are stunned. They couldn’t imagine how one of their fellow students could be a terrorist, a train bomber, that Youssef Mohamed -- this part of his name has been confirmed by the authorities -- had been arrested at around 4 a.m. at Kiel's central train station, while they were still sleeping.

He was a "completely normal guy" says Kamil, a 22-year-old Polish student from the border city of Szczecin, who lived on the same floor as Youssef. "He was friendly, polite, inconspicuous," and he never spoke ill of anyone.

He was religious, says Imane, a 22-year-old economics student from Morocco. The Lebanese student prayed up to five times a day, visiting a prayer room that was set up in the basement of the student block. On the door there is a sign banning cellphones and a poster in which the Imam Ali mosque can be spotted in a pretty view of Hamburg's Uhlenhorst district. According to findings by the Hamburg Office for the Protection of the Constitution, this Islamic center is a meeting place for Shia supporters of Hezbollah. However, Imane says that Youssef is a Sunni.

Nevertheless, the Hezbollah reference doesn’t seem to be all that absurd. The word in the student residence is that Youssef told other Muslims that his brother was killed three or four weeks ago during the Israeli military campaign against Hezbollah in Lebanon. But Imane wonders why he would look for revenge in Germany rather than against Israel.

Youssef led an unremarkable life in Kiel. His fellow students say that he wore jeans and t-shirts. But he would change his clothes during prayer times. Van Anh Nguyen, a young Vietnamese student, tells how Youssef wore long white robes when he went to pray. He also often visited a mosque on Dietrich Strasse in the Gaarden district of the city. The prayer leader there and the spokesman for the Arabic cultural association claim they can't remember Youssef. "Around 300 believers come to Friday prayers here," says al-Samaduni the spokesman.

He usually visited the prayer room in the basement, a meeting point for many of the Muslim students from the nearby houses. Their religious rituals didn’t always meet with the approval of those living in the house. "During Ramadan in particular they sang in the middle of the night," says Polish student Kamil, adding that they didn’t seem to think about sleep. And Nguyen says: "The men with beards scared me sometimes."

Youssef's room on the first floor was also a favorite contact point for devout Muslims. One of his German neighbors tells how Youssef had a lot of visitors: Arabs and North Africans. He also distributed leaflets about the Prophet Muhammad. At the start of the last semester, he moved from the ground floor to a different floor upstairs in the 1970s-era building, which has 40 rooms. He shared an apartment there with three German students and one other person. One of the beds was said to have been briefly occupied by a Moroccan, who has not shown his face so far. And there is speculation that he might be the second train bomber.