Pumwani , Kenya ( CNN ) -- Asha Mohamed sits in her cramped room in Pumwani slum clutching a tiny photo of her son , Harun . He 's dressed in a blue-striped tie framed by a crisp white T-shirt -- a typical 15-year-old Kenyan high school student . But in September he vanished . `` Harun woke up very early and asked his sister `` what time is it ? '' says Asha . He kept on asking her again and again . Then , at four in the morning , he left the house . '' In her heart , Asha knew where he had gone , but the text messages later confirmed it . Harun left his school and home in Kenya to fight for al Qaeda-linked Al Shabaab . `` It started when he was 14 . He came to me many times and said `` mom , I am going to Somalia to fight Jihad . '' I thought he was just playing . '' For years , Al Shabaab has targeted Somalis abroad to fight in their campaign to overthrown the weak transitional government . Now Kenyans , with no ethnic link to Somalia , are joining the Jihad . According to a recent U.N. report , there are `` extensive Kenyan networks linked to Al-Shabaab , which not only recruit and raise funds for the organization , but also conduct orientation and training events . '' Many of those events centered on Pumwani , a largely Muslim slum in Nairobi . Here , residents and religious leaders speak of a charismatic young Kenyan Sheikh that arrived from Mombasa . They say he bravely stood up to corruption , promoted the Quran , and generously handed out scholarships to young men . And he stoked their passion for Al Shabaab . The man is Sheikh Ahmad Iman Ali -- now the leader of Al Shabaab 's Kenya cell . He is remembered fondly at the Maratib Islamic Center in Pumwani . `` He was fearless and , at the same time , kind , '' says Abdullah Kilume , the administrator of the center . `` The majority think he was a good man , he did a lot of good , they saw what he did . '' Sheikh Iman would conduct lengthy sermons at the center 's mosque , says the U.N. report . The sermons were called 'Jihad Training sessions ' and many of them are posted on the internet . According to the U.N 's investigations , training sessions included classroom based lectures about 'Islamic Struggles ' in Afghanistan , Iraq and Yemen . Many of the children wore `` Jihad is our Religion '' T-shirts . Kilume remembers Sheikh Iman 's teachings well . He said that he appealed to the Kenyan youth of Pumwani . `` It reached the youth . I personally know that some of them wanted to go to Somalia . '' But while parents in this area supported the Sheikh 's war on graft and welcomed his financial help in this grindingly poor place , they felt differently when their children started to vanish . `` I went to that mosque and caused havoc , but they did n't care , '' says Asha . `` Somalia , that is not his war , I do n't even know why they are fighting , so why should he leave here and go fight in something he does n't even understand . '' But increasingly , it seems , these Kenyan youth do see it as their fight too . Six of Harun 's school friends who attended the center also vanished , she says . Local authorities would n't comment specifically on the case , but they acknowledged that a problem exists . The youth , who fled face the prospect of fighting Kenyan soldiers , many of them Muslim , who are engaged in an incursion deep into Somalia to stamp out Al Shabaab . Kilumi , the Muslim Center administrator , says he can accept it if these Kenyan recruits to Al Shaabab end up killing Kenyan soldiers . `` Like every other Muslim , I would like the Sharia law to be implemented and that is what they want to do in that part of Somalia , '' he says . `` Muslims first , Kenyans second . '' Sheikh Iman 's recruiting and fundraising drive has apparently been so successful that he has been rapidly promoted through the ranks of Al Shabaab . In 2009 he moved his base to Somalia , where it 's believed that he commands a force of between 300 and 500 Kenyan fighters . In January a video of the sheikh was posted on jihadi websites . It 's not known when the video was recorded . It shows him seated cross-legged in battle fatigues . Sheikh Iman called again for Kenya 's youth to cross over the border to fight . And if they couldnÂ¹t , he gave them a simple message . `` Raise your sword against the enemy that is closest to you . Jihad should now be waged inside Kenya . ''
Mom tells how her teen son living in a Kenyan Muslims slum was one of at least six persuaded to join the Maratib Islamic Center -linked Al Shabaab . at least six mom said : `` Why should he leave here and go fight in something he does n't even understand '' Kenyan Muslim say a charismatic iman taught the poverty-stricken kids about 'Islamic Struggles ' But the iman is remembered fondly by others at the Kenyan center where he groomed children for jihad .