Ukraine's former President Leonid Kuchma has denied any involvement in the murder of investigative journalist Georgiy Gongadze in 2000.
Mr Kuchma said he was ready to go "through hell" to prove his innocence.
He was speaking after arriving for questioning at the prosecutors' office in Kiev, a day after a criminal case was opened against him.
Mr Gongadze, a critic of Mr Kuchma, was abducted in September 2000. His headless body was found months later.
The Gongadze affair sparked massive street protests against Mr Kuchma's government at the time.
"I feel calm because I don't feel my guilt," Mr Kuchma said on Wednesday, after arriving at the prosecutor general's office in the Ukrainian capital.
Georgiy Gongadze's headless body was found in a forest
"For 10 years I've lived under severe pressure. But today I am morally ready to go through all the torments of hell so everybody knows what I've done and what I haven't done."
He also reiterated his belief that the Gongadze affair was a "horrible provocation against Ukraine and its president".
On Monday, prosecutors said Mr Kuchma, who served as president from 1994 to 2005, was suspected of abuse of power and giving illegal orders to the interior ministry which led to the killing of the reporter.
The prosecutors also said the former president was now banned from leaving the country.
Mr Gongadze - who was the founder of the Ukrainska Pravda (Ukrainian Truth) website - had exposed high-level corruption and was an outspoken critic of Mr Kuchma.
In the early 2000s, the anti-Kuchma opposition claimed it had the proof that the former leader was involved in Mr Gongadze's murder, pointing to audio tapes secretly recorded in Mr Kuchma's office by one of his bodyguards.
The tapes contain a voice resembling that of Mr Kuchma and suggesting that Mr Gongadze should be "kidnapped by Chechens".
Mr Kuchma has not denied the voice in the recordings was his but insists it has been doctored to make him appear to say things he had not actually said.
Although the authenticity of the tapes - which caused a sensation in Ukraine at the time - has been repeatedly questioned, prosecutors on Tuesday said that they would be recognised as valid evidence in the case.
In 2009, Ukrainian officials arrested former interior ministry official Olexiy Pukach, who later confessed to personally strangling Mr Gongadze and then beheading him with an axe. Three other officials are serving jail terms for their part in the killing.
Prosecutors earlier said that former Interior Minister Yuri Kravchenko, now dead, ordered Mr Gongadze's killing.
Mr Kravchenko is said to have committed suicide in 2005 - his body was found with two gunshot wounds to the head.
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