(Adds Bhutto news conference, paragraphs 8, 9) By Simon Cameron-Moore KARACHI, Oct 25 (Reuters) - "Welcome Home Benazir Bhutto". The message on hoardings looming over Karachi's streets seemed to possess a chilling sub-text a week after the suicide attack that killed 139 people during what was supposed to have been Bhutto's triumphant homecoming. The ensuing security scare means former prime minister Bhutto has not left Karachi since, although her aides said on Thursday she would visit her ancestral home near the city of Larkana in the north of Sindh province over the weekend. Hundreds of thousands of supporters came out to greet Bhutto on her return from eight years of self-imposed exile, and she will expect another big turnout in the family's feudal fiefdom, regardless of the assassination threat against her. On Thursday a new officer took charge of the investigation into the suicide attack by at least one bomber, possibly two, after Bhutto complained that the policeman originally appointed had been present when her husband Asif Ali Zardari was tortured while in custody in 2000. Government officials have blamed the attack on Islamist militants based in tribal areas where al Qaeda and Taliban fighters operate near the Afghan border, but Bhutto has said influential members of the Pakistani establishment are also out to get her. A statement issued by her Pakistan People's Party (PPP) suggested that the head of one of Pakistan's security agencies, Intelligence Bureau Chief Ijaz Shah, was one of the people Bhutto had named in a letter to President Pervez Musharraf. Bhutto, whose PPP is the largest opposition party, again expressed her disatisfaction with the conduct of the investigation, repeated a request for foreign experts to be involved in the probe along with demands for better protection. "I should be made to feel secure, I should not be made to feel insecure," Bhutto told a news conference. Bhutto and General Musharraf have begun a rapprochement ahead of elections due in January as part of a transition back towards civilian-led democracy. There is some speculation they could end up sharing power in a partnership that would have the blessing of the United States. Rising militancy in nuclear-armed Pakistan is causing unease among Western allies. On Thursday, a suspected roadside bomb or suicide blast killed 21 soldiers in northwest Pakistan's Swat valley, a tourist destination where a Taliban-style movement has taken root. KARACHI TENSE But it is Bhutto's return that appears to have caused great unease within the ruling Pakistan Muslim League (PML). While its leaders have reacted bitterly to Bhutto's comments about plots against her, little has been heard from Musharraf since the attack in Karachi. Nor has there been any breakthrough in the investigation. "I will get the case file today, read and analyse it and only then can I comment," said Deputy Inspector General Saud Mirza. In Karachi's Lyari neighbourhood, a PPP-dominated area, Bhutto supporters burnt tyres amd threw stones, and there was some shooting, as violence broke out over a remark by Sindh province's chief minister that Bhutto had "cast an ill-omen". Musharraf granted an amnesty in order to allow Bhutto to return without fear of prosecution in the old cases against her and her husband, Asif Ali Zardari. Neither of them has ever been convicted, and they have always maintained that the cases brought during the tenure of Nawaz Sharif, the civilian prime minister Musharraf deposed in 1999, were politically motivated.
