The wheelchair-bound petitioner who detonated a home-made bomb in protest at Beijing's international airport on Saturday is under criminal detention, mainland media report, while his family say they have lost contact with him. "My brother was so miserable with his injustices, and now, we don't know where he is and what he was arrested for," Ji Zhongji, elder brother of bomber Ji Zhongxing, told the Post yesterday. My brother was so miserable with his injustices, and now, we don't know where he is and what he was arrested for Ji Zhongji, elder brother of bomber Ji Zhongxing Ji, a 34-year-old native of Shandong province, had petitioned authorities in Beijing, Guangdong and Shandong for eight years over the crippling injuries he claimed to have suffered as a result of police brutality in Dongguan in 2005. He set off the device packed with gunpowder from fireworks in Terminal 3 of Beijing Capital International Airport. He survived the blast but had his left hand amputated. There were no other injuries. At about midnight yesterday, after surgery at Jishuitan Hospital, he was taken away in an ambulance under police escort to an unknown destination, Shanghai Daily reported. Video: Beijing airport explosion (WARNING: Video contains graphic images) The Beijing News reported that police had detained Ji while they investigated how he arrived at Beijing airport from Shandong, how and when he made the explosives and whether he had an accomplice. But the report said police refused to discuss his case further. Beijing police could not be reached for comment. Ji Zhongji, the elder brother, said the family had lost contact with Ji. "We are only farmers and migrant workers and have no idea how to help him," he said. "But I'm sure he never meant to hurt anyone else in the blast. He just wanted the public to know his suffering." Southern Metropolis Daily reported that a friend of Ji, also disabled, helped Ji call a taxi to take him to the long-distance bus station from where he set out to Beijing on Saturday morning. Ji had written on his blog that he had been beaten and left paralysed by security officers in Dongguan's Xintang village in June 2005 while driving a motorcycle taxi. He had been petitioning in vain for compensation and to demand that his attackers be punished. Public security officials in Guangdong ordered their colleagues in Dongguan to reopen the case and launch a through investigation. According to the Dongguan petition office, Ji filed a lawsuit against the Xintang village committee in January 2007, seeking 340,000 yuan (HK$425,000) in compensation. Dongguan People's Court rejected the claim in July 2007 on the grounds of insufficient evidence, and the city's intermediate court upheld that decision in January 2008. In March 2010, the township police gave Ji 100,000 yuan before closing the file. "Ji lost the case even though his passenger, Gong Tao, wanted to be a court witness to prove that Ji was badly beaten by auxiliary police officers," said Xu Mingyong , a Dongguan lawyer who represented Li at the time. "The security men insisted Ji had fallen from his motorcycle himself. And, in the end, Gong failed to show up in court because he had lost his ID card. "The court said the evidence we collected - including Gong's statement and records from the hospital - were not enough to prove Ji had been beaten by the men," the lawyer said. "I hope the new investigation will sweep away any doubts about this case."