Stephen Curtis, managing director of Group Menatep, the parent company of Yukos, died late Wednesday when his helicopter crashed in southern England. He was 52.

Police and civil aviation authorities in Dorset said that two men had died in a helicopter crash in a field near Bournemouth airport at around 7:40 p.m., but declined to identify the men or speculate on the cause of the crash.

A lawyer by training who was instrumental in creating Menatep's vast network of offshore structures in the 1990s, Curtis, a British citizen, was appointed to direct the embattled group in November after its principal shareholder, billionaire Mikhail Khodorkovsky, was arrested at gunpoint and jailed on charges of fraud and tax evasion. Curtis replaced Khodorkovsky's partner, Platon Lebedev, who was jailed on similar charges in July.

News of the incident came as Swiss police conducted nationwide raids on companies connected to Yukos at the request of Russian authorities, who have placed several core Menatep shareholders on Interpol's wanted list for allegedly taking part in massive fraud.

Swiss prosecutors said in a statement that police raided offices and homes of people connected to the company in Zurich, Geneva, Schwyz and Freiburg. Officials in Bern could not be reached for comment late Thursday, and the statement did not disclose the names of the companies or people involved.

The statement, however, did say prosecutors would hand over documents seized during the raids to Russian authorities and that they were acting in response to an official request on a case involving membership in a criminal organization, embezzlement and fraud.

Prosecutors also said the individuals targeted in Thursday's raid participated in fraudulent trading deals involving fertilizer, oil and oil products. The revenues from these deals were allegedly laundered through Swiss companies and bank accounts, the statement said.

According to documents obtained by The Moscow Times, Curtis played a central role in building Menatep's vast offshore empire, which is now worth dozens of billions of dollars. He was a key lawyer for Menatep since at least 1997, when Yukos was under fire from minority shareholders who accused it of redirecting corporate profits into offshore accounts linked to Khodorkovsky and his partners. Working out of his law firm's plush Park Lane office, which shared an address with a Yukos subsidiary, Curtis later oversaw efforts to consolidate some of those profits back onto the company's balance sheet.

As a result of his work for Khodorkovsky and Lebedev, Curtis amassed a vast fortune and literally lived in a castle -- the 19th century Pennsylvania Castle in Portland, Portsmouth. He was also the owner of the helicopter that crashed, his personal assistant said by telephone from Pennsylvania Castle.

Police said Thursday they had not been able to identify those who perished because the helicopter exploded on impact, burning the bodies. They said it would take "months" for the investigation of the incident to run its course.

"We have no official confirmation it was him," Curtis' assistant said. "But we are almost completely certain. He was making his usual trip home. There was nothing out of the ordinary."

Andy Martin, news editor of The Daily Echo in Bournemouth, said by telephone that Stephen Curtis lived in the area and that local investigators are concentrating on weather conditions as the primary cause of the crash.

"It wasn't great weather, but it wasn't too bad," Martin said.

Martin said that witnesses reported hearing the helicopter flying overhead, followed by silence, then a crash and an explosion that sent a fireball 10 meters into the sky. "The explosion was on impact," he said.

Members of the Dorset Fire and Rescue service arrived on the scene within minutes to find the helicopter "engulfed in fire," said Steve Shuck, divisional officer of Dorset Fire and Rescue Service.

Shuck, however, said that while the weather had been "rainy and misty" Wednesday evening, it was just "typical English weather."

However, an aide to core Yukos shareholder Leonid Nevzlin said Thursday he didn't rule out foul play. "The only thing we can say is that this is a great loss. He was a personal friend as well as a colleague," the aide, Eric Wolf, said by telephone in Israel, where Nevzlin lives in exile.

Nevzlin said recently that he had received "threats of a personal nature" almost daily from people claiming to be Kremlin intermediaries.

Curtis' personal assistant, who spoke on condition of anonymity, said he did not know whether Curtis had been threatened recently.

Boris Berezovsky, founder of Yukos' merger partner Sibneft who now lives in exile in London, said Curtis had also worked for him on "various financial matters." He refused to elaborate.

Berezovsky said he met Curtis regularly but did not know whether he had been threatened.

Two years ago, Menatep made Russian corporate history by becoming the first major financial-industrial group to go public with its ownership structure, a move that capped the group's remarkable drive to the top of corporate governance rankings. But with the political and legal pressure on the company mounting, the company has decided to retreat back into the shadows by overhauling its ownership structure.

Although the new Menatep structure has not yet been made public, analysts say it is likely that major shareholders have transferred their stakes to front companies in a bid to hide their links to the company and stave off asset seizures.

Khodorkovsky's attorney, Anton Drel, said Curtis was not involved in this process.

(The Moscow Times 5.iii.04)