Baghdad, Iraq (CNN) Tariq Aziz, the imprisoned former Saddam Hussein lieutenant who served as a public face of the Iraqi dictator's government until the regime was toppled in 2003, died Friday of a heart attack at a hospital, two officials in the Mideast nation said.

He was 79.

Aziz, who'd been sentenced to death four years ago in one of several post-Hussein trials against him, died at a hospital in the southern Iraqi city of Nasiriya, said Hussein al-Askay, the head of a Nasiriya prison, and Saad al-Majid, the director of the province's health department.

Aziz had been taken to the hospital after his medical condition deteriorated at the prison, the officials said.

Aziz often defended the Hussein regime on the international stage, serving as deputy prime minister from 1981 to 2003 and as foreign minister for part of that time.

A fluent English speaker, he was the face of the regime to the outside world. When a U.S.-led coalition invaded Iraq to oust Hussein in 2003, he was the eight of spades on the deck of cards handed out to U.S. troops, representing the U.S. military's list of 55 most wanted Iraqis.

He appeared frail when he testified at Hussein's 2006 trial on war crimes charges, for which the ousted dictator was hanged later that year. At a subsequent trial in 2010, Aziz was convicted and sentenced to death for his alleged role in persecuting and murdering members of religious parties in the 1980s.

A rare Christian in Iraq's hierarchy

Aziz, a member of Iraq's tiny Christian minority, was born Michael Yuhanna in 1936 in Mosul and later changed his name.

His association with Hussein stretched back to the 1950s, when both were activists in the Baath Party, which was then banned.

Aziz rose with Hussein after the latter became president in 1979, eventually taking the office of deputy prime minister. His religion made him a rarity in Hussein's Sunni Muslim-dominated hierarchy.

Aziz became well known to Westerners during the first Gulf War , when he served as Iraq's foreign minister.

In the run-up to the 2003 invasion, Aziz again represented his country abroad, traveling to Rome to meet with Pope John Paul II , who opposed military action. He also made some public appearances, including one to squelch rumors that he had defected or been shot.

Before the start of the war, he said he would rather die than be taken into U.S. custody.

But more than a month after it started, he left a relative's Baghdad home and turned himself in to U.S. troops.

'They'll find a way to kill me'

Aziz testified, but was not among the eight defendants, at Hussein's trial, in which an Iraqi tribunal charged the former President with a variety of crimes, including Iraq's 1990 invasion of Kuwait and the gassing of Kurds in the 1980s.

But Aziz was charged in a number of other cases, including the 1992 executions of 42 merchants. In that case, the merchants, who worked in Baghdad's wholesale food market, were arrested, convicted of profiteering and executed after being accused of driving up food prices.

Aziz was among several former officials convicted in that case in 2009, and was sentenced to 15 years in prison.

A year later, he was convicted and sentenced to death for the Sunni-dominated regime's persecution of religious parties, including the Shiite Dawa party.

His lawyer, Badi Arif, told CNN in 2011 that the death sentence was politically motivated.

"Mr. Aziz used to always tell me, 'They'll find a way to kill me, and there is no way for me to escape this,' " Arif said.