KARACHI, Oct 24 (Reuters) The baggage of Benazir Bhutto's past dogged a probe into last week's assassination attempt against her that killed 139 people, as Pakistani officials said the police officer in charge had been forced to step aside.
The chief investigating officer, Manzoor Mughal, opted to take leave, according to Interior Ministry spokesman Javed Iqbal Cheema, after Bhutto complained that he had been present when her husband, Asif Ali Zardari, was tortured while in custody in 1999.
Members of Bhutto's Pakistan People's Party (PPP) had also criticised Mughal's handling of the crime scene after a suicide bomber, or possibly two, attacked her homecoming procession in Karachi on Friday.
Government officials say the attack was carried out by Islamist militants linked to northwestern tribal areas where al Qaeda and the Taliban are based.
But Bhutto has sown seeds of mistrust by saying she had informed President Pervez Musharraf of three influential members of the establishment involved in a plot against her.
The investigation has yet to make a breakthrough and, while some people have been picked up for questioning, no one directly involved in the attack has been arrested.
Musharraf granted an amnesty to politicians accused of crimes during the 1990s in order to allow Bhutto to return from eight years of self-imposed exile without fear of prosecution in graft cases against her.
But police were still raking over related cases.
MIDNIGHT KNOCKS On Monday and last night they raided the house of Zulfiqar Mirza, one of Bhutto's most trusted aides, to arrest him over a murder in 1998, but Mirza was not at home.
''They come after midnight to harass us,'' his wife Fehmida Mirza, a member of parliament for the PPP, told Reuters.
Mirza accompanied the former prime minister on her return to Karachi last week to help co-ordinate her security.
He is wanted in connection with the murder of former Pakistan Steel Mills chairman Sajjad Hussain, who was gunned down three days before he was due to testify before a panel investigating allegations of corruption against Zardari.
Zardari, who was nicknamed ''Mr Ten Percent'', was imprisoned for eight years before being released in 2004, five years after General Musharraf led a coup that overthrew then prime minister Nawaz Sharif.
While Bhutto and Musharraf have begun a rapprochement as part of a planned transition to civilian-led democracy, the opposition leader has plenty of enemies among Musharraf's political allies.
PPP officials said the police action against Mirza was politically motivated.
''The police are victimising people in charge of Benazir Bhutto's security, so that they go underground and can't protect her, and thereby restrict her movement,'' Jameel Soomro, the party's media coordinator, said.
There is speculation that Bhutto and Musharraf could share power after a national election, and the United States is believed to be quietly encouragi& their partnership.
The pair are seen as progressive, pro-Western leaders who will support NATO efforts to stabilise Afghanistan and fight al Qaeda militants in nuclear-armed Pakistan.
Musharraf, whose re-election by parliament while still army chief is the subject of continuing Supreme Court challenges, has promised to quit the army if he is granted a second term.
His position will be weakened after parliamentary elections due by early January unless the ruling PML does better than expected or finds new coalition partners.
REUTERS SG RK1853