New information on the suspect, Malik Mumtaz Qadri, has raised speculation Taseer's killing may have been a political conspiracy and not the act of a lone religious extremist, Dawn reported. It had been alleged Qadri, a member of the elite security guard, had acted in retaliation for Taseer's opposition to Pakistan's harsh blasphemy laws.
Taseer, a member of the Pakistan People's Party and a highly regarded liberal, was shot and killed Tuesday in Islamabad and Qadri was later reported to have surrendered.
"Every aspect is being considered," an official said, responding to questions about the Qadri investigation, Dawn reported, adding suspicion was rising as a number of officials had confirmed Qadri had been posted out of police's special branch about 18 months ago after a report by then Regional Police Officer Nasir Khan Durrani described him as a "security threat."
CNN, quoting authorities, reported a provincial police official had banned Qadri five months ago from security duty for senior officials because he held extremist views.
CNN said Pakistani intelligence agencies had warned about Qadri in 2004 after claiming they'd found connections between him and the Sunni religious group Dawat-e-Islami.
There have been a number of sectarian killings in recent months in Pakistan, along with those by the Taliban and other militants.
Dawn reported a team was questioning eight personnel of the Elite Force who reportedly did not stop Qadri when he allegedly began shooting.
Taseer's state funeral Wednesday drew thousands of mourners, including Prime Minister Yousaf Raza Gilani, the BBC reported.