During Mr Kim Young Sam's presidency, two former presidents, Chun Doo Hwan and Roh Tae Woo, were jailed for treason, insurrection and taking bribes.

ECONOMIST: South Korea

Choi refused to take part in the trial of his convicted successors Chun Doo Hwan and Roh Tae Woo, the men who ousted him from power.

CNN: NEWSMAKERS

He was convicted in 1996 of bribing former South Korean president Roh Tae-woo but pardoned a year later by then-president Kim Young-sam.

WSJ: South Korea Plans to Pardon Former Samsung Chairman

Chun Doo-hwan and Roh Tae-woo, both former presidents, went to jail for soliciting hundreds of millions of dollars from the country's biggest business groups.

ECONOMIST: Roh Moo-hyun

Roh is the nation's third former president to be summoned, following in the footsteps of Chun Doo-hwan and Roh Tae-woo, both of whom were convicted in 1995 of receiving bribes and inciting a mutiny.

CNN: South Korea's Roh apologizes to nation