A prominent Western investor who has clashed with Russian authorities said Tuesday that a lawyer who advised his fund died in a Moscow jail after being denied medical care.

Russian attorney Sergei Magnitsky died Monday night in the
Matrosskaya Tishina pretrial detention center after developing
pancreatitis that was not treated, said William Browder, CEO of
London-based Hermitage Capital Management.

Magnitsky's death is likely to deepen Western concerns about the
risks faced by anyone who challenges the authorities in Russia.
Several independent journalists and human rights activists and
lawyers have been the victims of unsolved slayings in recent years.

Russian Interior Ministry and prison officials could not
immediately be reached for comment.

Hermitage was once the largest investment fund in Russia. But
Browder, a British citizen raised in the U.S., was barred from
Russia four years ago by authorities citing national security
concerns.

Observers have said he may have made enemies in one of his many
high-profile campaigns for greater transparency and efficiency at
some of Russia's biggest conglomerates, most of which have close
ties to the state.

Browder alleges his fund was targeted in a multimillion-dollar
fraud and forgery scheme involving Interior Ministry officers.

He said Magnitsky had been involved in defending Hermitage and
its partner HSBC against the scheme, which Browder said involved
illegally taking over assets and using them to fraudulently reclaim
$230 million in taxes from the state.

Magnitsky was arrested last November on tax-evasion accusations
linked to his work with Hermitage. The fund said after the arrest
that the lawyer had apparently been targeted for providing
accounting advice to two Hermitage Fund entities that police
claimed underpaid taxes in 2001.

Browder said he was arrested by the same police officers he had
implicated in the alleged fraud, and called him "a brave and
innocent man" railroaded for seeking justice.

"He entered prison as a healthy 37-year-old and exited the
prison dead," Browder told The Associated Press by telephone. "We
are going to call for an investigation into all the circumstances
surrounding his death."

He said Magnitsky had developed pancreatitis in jail and was
repeatedly denied medical attention when he asked for it. In a
statement, Hermitage Capital Management said lawyers for Magnitsky
were told he died of a ruptured abdominal membrane.

The statement said Magnitsky had not been able to see his mother
and his wife or to speak to his two children during nearly a year
in pre-trial detention. It said his mother learned of death Tuesday
morning, after she went to another jail to bring him personal items
and was told he had been transferred to Matrosskaya Tishina on
Monday.