CAIRO -- The biochemist detained in Cairo in connection with the London bombings is an intelligent, quiet young man who advanced to one of Egypt's most prestigious research centers and whose lower middle-class family spent heavily for him to study abroad, neighbors say.
Magdy el-Nashar, 33, had been teaching chemistry at Leeds University in northern England, and returned to Egypt several days before the deadly July 7 bombings in the British capital.
Nashar's brother Mohammed said Nashar was arrested Thursday, after he'd gone to pray at a local mosque and did not return.
A security official said Britain was pushing Egypt to hand Nashar over. If Egypt does so, it may also seek the return from Britain of other militant suspects, the official said, speaking on condition of anonymity for security reasons.
In questioning by Egyptian officials, he denied any role in the attacks and said he was planning to return to Leeds after a vacation in Egypt, the Interior Ministry said in a statement. He was still being held, the ministry said, without saying whether he would be handed over to Britain.
British authorities said they found signs in Nashar's Leeds home that quantities of a compound called TATP, or triacetone triperoxide, had been converted into a powerful explosive, The Times newspaper reported.
Nashar grew up in Cairo's crowded, impoverished Ezbet Fahmy section. His father, retired from a construction company, owned a welding shop next to their apartment. Several years ago, his family moved to a somewhat better neighborhood.
''They were very isolated from people. He [Nashar] was rarely seen talking to people," Rifai Sayed Taha, whose brother is married to Nashar's sister, said.
His youngest brother, Mohammed, said Nashar returned to Egypt on June 30 and was arrested on Thursday. Nashar was vacationing in Cairo, said the brother.
''I believe in his innocence. Ask anyone in the street or at the college, they will say that all his attention was focused on his studies and research," said Mohammed Nashar, who is in his late 20s. ''I want the whole world, America and the British, to know that we know nothing and don't know why this is all happening."
Nashar studied chemistry at Cairo University and for his doctorate studies was accepted by the National Research Center, one of Egypt's most prestigious institutions. In late 1999, the center sponsored him for a winter semester at North Carolina State University in Raleigh, and then for the teaching and research position at Leeds, where he moved in 2000.
Leeds University said he earned a doctorate in May. His research focused on biocatalysis and enzyme immobilization, according to a biography of him at the university's website.
That kind of research ''wouldn't have anything directly to do with explosives" or with biological weapons, said Constance Ann Schall, an associate professor of chemical engineering at the University of Toledo in Ohio.