Allegations that Roh, president from 2003-08, accepted $6 million in bribes from a businessman while in office weighed heavily on the ex-leader, who appeared emotionally wrought last month as he prepared to face prosecutors.
Roh hurled himself off a 100 foot (30 meter) high cliff early Saturday while hiking, trailed by a security guard, near his home in Bongha, police in the nearby southern port city of Busan said.
Life had become unbearable and "too many people are suffering because of me," Roh wrote in a note found on his computer, police said.
"What's left for me for the rest of my life is just to be a burden to others," his note said. "Don't be too sad. Aren't life and death both part of nature? Don't feel sorry. Don't blame anybody. It's destiny." He asked to be cremated, a small gravestone erected near his home.
Roh's suicide stunned the nation. At train stations and shopping malls across the country, South Koreans were glued to TV monitors.
Many snapped up special newspaper editions about Roh. Tens of thousands flooded his Web site, many posting condolences.
"I was utterly shocked," said Chun Soon-im, 63, of Seoul.
"They say 'hate the sin but not the sinner,' and that's how I feel. The investigation must continue and we must get to the truth, but I cannot help feeling sorry for the man and those left behind."
Mourners wailed as Roh's coffin, draped in red, returned to Bongha from a Busan hospital. His two children, sobbing, followed the casket to the community center near his birthplace of Gimhae, some 280 miles (450 kilometers) from Seoul. Hundreds lined up late in the night to pay their respects.
In the capital, more than 2,500 people held a somber candlelight memorial service at a makeshift mourning site, many bowing, burning incense and leaving white chrysanthemums, a traditional Korean symbol of grief.
In Washington, President Barack Obama said he was "saddened" by the news and offered his condolences to Roh's family and the South Korean people.
Roh's is the latest high-profile suicide in a country with the highest suicide rate among the 30 nations in the Organization for Economic Cooperation and Development.
The corruption allegations against Roh were by no means the worst leveled against a South Korean president.
In 1997, two ex-presidents were convicted of pocketing hundreds of millions of dollars in bribes while in office. Chun Doo-hwan, president from 1981-88, was fined $270 million; Roh Tae-woo, leader from 1998-93, was fined $350 million.
But the accusations were deeply shameful to Roh, who built a reputation as anti-corruption crusader.
"I feel ashamed before my fellow citizens. I am sorry for disappointing you," Roh told supporters three weeks ago before turning himself over to prosecutors who grilled him for more than 10 hours.
During the interrogation, Roh denied the allegations against him, the prosecution spokesman Cho Eun-sok said.
He previously acknowledged that a local businessman indicted in December in a separate bribery scandal - gave his wife $1 million, which he did not consider a bribe. He also said he was aware the man gave $5 million to another relative but thought it was an investment.
Prosecutors suspect all $6 million eventually reached Roh, and were expected to announce soon whether they would seek to arrest him. His wife and children also were summoned for questioning, and last week his elder brother was sentenced to four years in prison in a separate bribery scandal.
A worried Roh wasn't eating properly and had taken up smoking recently, news reports said.
Roh's backers accuse conservative supporters of President Lee Myung-bak, who took over from Roh in February 2008, of carrying out the probe as political revenge. Near Seoul's City Hall, Roh supporters stood in line to sign a petition seeking Lee's impeachment.
Lee, who learned of Roh's death just before a summit with European Union officials, appeared grim Saturday. He found news of Roh's death "truly hard to believe," spokesman Lee Dong-kwan quoted him as saying.
Roh's death was a tragic end for the humble son of farmers who never attended college but still managed to pass the country's tough bar exam in 1975 and opened his own practice three years later.
He forged a reputation as a human right lawyer, defending students accused of sedition under previous military-backed administrations. He once was arrested and his law license suspended for supporting an outlawed labor protest.
Roh's political career took off with his election as a liberal lawmaker to the National Assembly in 1988.
His ascension to the presidency came in a surprise 2002 election win on a campaign pledge not to "kowtow" to the United States, one that resonated with young voters.
But in 2004, Roh made the costly misstep of urging voters to support candidates from his Uri Party in a violation of political neutrality laws. He was impeached, then reinstated months later after a court ruled in his favor.
Roh maintained liberal predecessor President Kim Dae-jung's "sunshine policy" of offering North Korea aid to facilitate reconciliation, holding a summit in Pyongyang with North Korean leader Kim Jong Il in 2007, the second such meeting between leaders of the two countries that technically remain at war.
"I lost my lifetime democracy movement comrade. I feel like half of my body has collapsed," Kim said, according to an aide.
Though criticized as inexperienced and confrontational by some, Roh was praised by others as a humble, candid leader who pushed for political reform and fought against corruption.
"He shocked us twice: first, by betraying our trust in him as the keeper of justice when it was revealed that he'd received the illegitimate money; now, in showing that he was not even responsible enough to face the consequences of his action," said Kim Hye-jung, 35, of Seoul. "As a supporter of the values he stood for, I feel greatly let down."
Roh is survived by his wife, Kwon Yang-sook, son Roh Gun-ho and daughter Roh Jeong-yeon. Funeral arrangements were not immediately available.
--- Associated Press writers Jae-soon Chang, Hyung-jin Kim, Kwang-tae Kim and ShinWoo Kang contributed to this report.
NEW YORK AND TRI-STATE AREA NEWS
SEND TIP OR PHOTO || REPORT TYPO || GET WIDGET
EYEWITNESS TWITTER || FIND US ON FACEBOOK