The future of Ukraine as an independent democratic state hangs in the balance. President Leonid Kuchma stands accused of complicity in the murder of Georgy Gongadze, a journalist whose headless and mutilated body was identified this week, months after his disappearance. The revelations about Mr Kuchma's alleged involvement in a host of crimes from murder to corruption came from his former bodyguard who, after bugging the president's office, leaked tapes which - if proved authentic - are a devastating indictment.

In the Financial Times this week, Mr Kuchma endorsed an investigation, even suggesting that foreign experts should be included. While this was a praiseworthy gesture, it cannot become reality unless Mr Kuchma stands aside and allows the investigation to go forward. For, as his letter shows, even as he claims to support an investigation, Mr Kuchma takes any opportunity to lash out at his opponents.

If Mr Kuchma remains recalcitrant, continues to harass political opponents and the media and drags his feet on the investigation, he risks relegating Ukraine to the same fate as neighbouring Belarus, where a repressive regime silences political opposition.

The outside world cannot stand idly by. Western governments are already deeply involved in Ukraine. Among former Soviet republics, Ukraine has been the single biggest recipient of US aid. Between 1991 and 1997, the European Union and member states gave Ecu4.2bn, of which Ecu1.8bn was in grants. Since the early 1990s, the World Bank has approved more than Dollars 3bn in loans and grants and two guarantee operations totalling Dollars 220m.

This large-scale western involvement was motivated mainly by geopolitical considerations. I, too, have been deeply engaged in Ukraine but my aim has been to help it make the transition from a closed to an open society. I established the Ukrainian Renaissance Foundation in 1989, two years before Ukraine became an independent country. Since then I have given more than Dollars 100m to support Ukraine. I provided foreign experts who helped it gain access to the International Monetary Fund and the World Bank shortly after Mr Kuchma became president.

I first met Mr Kuchma when he was a candidate in the 1994 presidential elections. Richard Nixon, former US president, had invited us both to lunch. As fate would have it, on that day Mr Nixon died and Mr Kuchma and I dined alone. He impressed me as someone more energetic and dedicated than his predecessor.

After his promising start, I watched the decline in Mr Kuchma's performance with dismay. I observed the pressure on independent media and the use of questionable methods during his campaign for a second five-year term. I publicly cautioned the west against tolerating the president's excesses because of Ukraine's sensitive geopolitical position. I warned that his re-election had strengthened the hand of corrupt oligarchs who had bankrolled his campaign.

I last saw Mr Kuchma in November. It was a one-on-one meeting in Kiev. I was taken aback by the president's scathing, virulent remarks about Viktor Yushchenko, Ukraine's prime minister, and Yulia Timoshenko, the former deputy prime minister. I told him that earlier that day I had seen Mr Yushchenko, who had professed loyalty to Mr Kuchma. I pleaded that it would be better for the future of his country if the two politicians could somehow work together. And later I found myself in the uncomfortable position of urging Mr Yushchenko to accommodate the president. But that was before the disclosure of Mr Kuchma's possible role in Gongadze's assassination.

Ukrainian public opinion is demanding an independent investigation into the circumstances of Gongadze's death. Protests, which are growing in strength, call for an investigation and, increasingly, for Mr Kuchma's resignation. If Mr Kuchma cares about Ukraine's survival as an independent democratic state, he must take responsibility for his actions and hand over his duties to the prime minister, the constitutionally designated successor, pending the results of the investigation. The west must take a clear position, denouncing Mr Kuchma's behaviour and actions. There is no way for the international community to continue to do business with Mr Kuchma until an impartial investigation has been completed and those responsible are held to account. The population needs to know that the west stands with them, opposing any attempt by Mr Kuchma to evade responsibility and, ultimately, the law.

I remain committed to helping the development of open society in Ukraine. I urge other donors to maintain their support for civil society. It would be tragic if Mr Kuchma's failings were to compel the international community to abandon civil society in these most difficult times.