People watch a news program showing Jang Song Thaek, North Korean leader Kim Jong Un's uncle, escorted by guards during a trial in North Korea on Thursday. North Korea said Friday Jang had been executed as a traitor for trying to seize power, a stunning end for the man who had been the country's No. 2 official

SEOUL, South Korea — Jang Song Thaek rose from a municipal bureaucrat to North Korea’s No. 2 official — behind only leader Kim Jong Un.

His ties were more than political: Jang was Kim’s uncle, married to the leader’s aunt, Kim Kyong Hui.

Jang’s execution, announced early Friday, marked an unprecedented fall from grace of one of the most powerful figures in the country as well as its most serious political upheaval in decades.

The 67-year-old Jang held the posts of vice chairman of the National Defense Commission and member of the Political Bureau of the Central Committee of the Workers’ Party.

In late 2008, Jang was assumed to be serving in a regency role while the young Kim Jong Un was being groomed to succeed his father, Kim Jong Il. Jang often accompanied Kim Jong Un on guidance trips and stood at his elbow at public events.

A well-traveled operator with a network that spread to China, Jang was considered the chief architect of economic policy that focused on partnering North Korea with its ally.

Rumors of Jang’s dismissal began surfacing in Seoul earlier this month. On Sunday, he was fired from all posts at a special party meeting and dragged away by soldiers. Four days after his dramatic public arrest, Jang was tried for treason by a special military tribunal and executed, state media reported.

The list of crimes against Jang was long, with plotting to overthrow the leadership the most serious of the allegations. Jang confessed, according to Pyongyang’s official news agency.

State media portrayed Jang as a power-hungry and ambitious challenger to the throne who resorted to nepotism and favoritism to build his “little kingdom” as he plotted a coup against his nephew.

State media accused Jang of destroying the economy for his personal benefit, blaming him for masterminding the 2009 currency revaluation that resulted in rare protests in North Korea. He was held responsible for the shoddy quality of construction materials, charged with secretly trading in rare metals and was criticized for encouraging private enterprise.