Mr Roh served as South Korea's president from 2003 to 2008
The former president of South Korea, Roh Moo-hyun, who had been under investigation for alleged corruption, has apparently committed suicide.
A spokesman said Mr Roh, 62, appeared to have jumped into a ravine while mountain climbing near his home and had left a brief suicide note.
Last month, Mr Roh apologised over allegations his family took $6m in bribes during his 2003-2008 term.
He never admitted wrongdoing, but said he was sorry for disappointing people.
'Deeply sad event'
In a statement read live on national radio and television, Mr Roh's former chief of staff, Moon Jae-in, said the former president had left a suicide note.
"Former President Roh left his house at 0545 (2045 GMT on Friday) and while hiking on the Bonghwa Mountain, appears to have jumped off a rock at around 0640," he said.
"He left a short suicide note addressed to his family members."
In the message, Mr Roh described his life as "difficult" and apologised for making "too many people suffer", according to South Korean media.
"Don't be too sad. Isn't life and death all part of nature? Don't be sorry," the official news agency, Yonhap, quoted the note as saying.
"Please cremate me. And please leave a small tombstone near home. I've long thought about that."
Police said the former president had fallen 20-30m (65-100ft) down a mountain near his hometown of Gimhae and had been transported to Busan National University Hospital, where he was pronounced dead on arrival at 0830 local time (2330 GMT).
Hospital officials later said he had died from massive head injuries.
The apparent suicide - believed to be the first by a modern South Korean leader - has shocked the nation.
"This is a truly unbelievable, lamentable and deeply sad event," President Lee Myung-bak, Mr Roh's successor, said in a statement.
Medics said Mr Roh died from massive head injuries resulting from the fall
Mr Lee, who was told of the death while holding talks with Czech President Vaclav Klaus, told ministers to prepare Mr Roh's funeral with "respect and in line with the protocol for a former president".
Mr Roh's predecessor, Kim Dae-Jung, said he had lost his "life-long companion, with whom I took part in struggles for democracy and shared 10 years of a democratic government".
"Allegations concerning his family members have been leaked to the press every day," Mr Kim said. "He was probably unable to bear the pressure and tensions any longer. My heart goes out to his family."
On the streets of Seoul there were mixed reactions to the news.
"I'm heartbroken. I can't imagine how much pain he was in," Park Kyung-hee said. "I think death was the best choice for him so that those close to him didn't have to suffer."
Jang Soo-Dong, an engineer, said the media, "and prosecutors and others who fed them with unconfirmed allegations" should be held partly responsible.
But businessman Park Hae-Heon said Mr Roh should have "resorted to the legal system to prove what was right and wrong".
A human rights lawyer, Mr Roh took office in 2003 vowing to fight corruption, but correspondents say his term was a rollercoaster ride, with his Uri party hit by scandal and infighting.
2003 - elected president
2004 - suspended by MPs, then reinstated by court
2008 - leaves office
Apr 2009 - quizzed for alleged bribery
23 May 2009 - dies while mountain climbing
He was suspended early in 2004, after parliament voted to impeach him over a breach of election rules, but the Constitutional Court later overturned the move and he was reinstated.
Last month, Mr Roh was questioned over allegations that he had taken more than $6m in bribes from a wealthy shoe manufacturer, Park Yeon-cha, who was indicted in December on separate bribery and tax evasion charges.
The former president later apologised for the scandal.
"I feel ashamed before my fellow citizens. I am sorry for disappointing you," he said in a televised statement on 30 April.
Mr Roh admitted his wife had received $1m from Mr Park. However, he said it was a payment to help her settle a debt, and not a bribe.
He also said he was aware that the businessman had given another $5m to a relative, but that he thought it was an investment.
After Mr Roh's death was announced on Saturday, Justice Minister Kim Kyung-han said the corruption case against him would be formally closed. However, he did not say whether the former president's family would continue to be investigated.