Sanaa, Yemen (CNN) -- Umar Farouk AbdulMutallab disappeared in Yemen for more than two months before he allegedly tried to bring down a Northwest Airlines jet with explosives concealed in his underwear.
Investigators want to know if, during that time, he heeded the call to prayer coming from the hills above Yemen's capital, where an Islamic university headed by a fiery cleric has helped the country earn its reputation as an incubator of extremism.
The students who pray at Al-Iman University now, two weeks after that failed Christmas Day attack, say the school has been made a scapegoat, and that what AbdulMutallab is accused of having done is wrong.
"It's against Islam," one says.
"The thoughts in their heads go against Islam," says another.
AbdulMutallab's alleged attempt to ignite explosives as the jet approached Detroit, Michigan, resulted in a fire on his lap -- and serious burns -- before passengers and flight crew subdued him and put out the flames.
Al-Imam's leader is Sheikh Abdel Majid al-Zindani, a provocative cleric with a flaming red beard. The United States considers him a terrorist, accused in 2004 of supplying weapons to al Qaeda.
But in Yemen, al-Zindani is a free and influential man.
Al-Zindani denied CNN's request for an interview but allowed the network to tape at the school he's built from the ground up since the early 1990s.
Every year, thousands of Islamic students from Yemen, Africa and around the world are cocooned in al-Zindani's compound, where they study their faith and are instilled with a strident defense of that faith.
Last year, al-Zindani made a public plea to recruit millions of young men to fight jihad against Israel.
But the students say they don't think AbdulMutallab was ever at the school, and investigators don't appear to have come to ask. Yemeni authorities, it seems, have taken a hands-off approach to the university.
"To my knowledge, no security, no investigation teams came here," political science professor Ismail al-Suhaili said. "Nobody thought that AbdulMutallab was here."
In Yemen, Al-Iman University is highly respected and its leader admired, making it difficult for investigators to find out for sure if the Christmas Day bombing suspect was ever there.