Story highlights Authorities also threaten to arrest Musharraf if he returns

The former president has been in self-imposed exile for five years

The former general became president in a bloodless military coup in 1999

Benazir Bhutto was assassinated on his watch, and some blame him for not protecting her

The Pakistani Taliban vowed to assassinate former President Pervez Musharraf if he returns to the country as planned Sunday, a spokesman for the terrorist group said in a video message online.

Tehrik-i-Taliban will send out a "death squad" to kill him, Ehsanullah Ehsan said Saturday.

One of the squad members addressed Musharraf in English, demanding the former president surrender himself.

After resigning in 2008, Musharraf spent five years in self-imposed exile in London and Dubai.

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He plans to fly on a commercial airline into Karachi on Sunday, then attend a rally that will include Pakistani expatriates from the United States, Canada, the United Kingdom and the United Arab Emirates, he has said in a statement.

He plans to lead his political party into Pakistan's general elections slated for May.

In 1999, the then-chief of Pakistan's army became its president in a bloodless military coup. He remained in power until resigning in 2008 -- a period that included the U.S.-led invasion of neighboring Afghanistan.

A few months before he left office, Benazir Bhutto -- Pakistan's first elected female prime minister -- was killed in a gun-suicide bomb attack as she was wrapping up a campaign rally in Rawalpindi.

The attack, two months after she survived an assassination attempt in Karachi, fueled criticism that Musharraf had not done enough to protect Bhutto's life despite numerous threats. The former military ruler has denied having anything to do with Bhutto's killing.

He's been targeted by Pakistan authorities, who in August 2012 confiscated his property and froze his bank account.

A politician and a prosecutor have called for Musharraf's arrest as soon as he sets foot in Pakistan, according to media reports.