Islamabad, Pakistan ? A key investigator in the kidnap case of American journalist Daniel Pearl said late Saturday night that police have strong leads on Pearl’s whereabouts, but are not certain whether he is dead or alive.

An e-mail sent Friday purportedly by his abductors said the 38-year-old Wall Street Journal reporter had been killed and his body dumped in a Karachi graveyard because the kidnappers’ demands had not been met. But police searched more than 400 graveyards in and around the southern port and found nothing, causing them to conclude that the e-mail either had not come from the kidnappers or that they for some reason had lied.

A police officer stands guard outside the Christian Cemetery in Karachi, Pakistan, while other officers search inside the graveyard for missing U.S. journalist Daniel Pearl. Hundreds of Pakistani police searched cemeteries for evidence of the fate of Pearl, but by Saturday morning had discovered nothing to back an e-mail claim that the American had been killed and his body dumped in a graveyard.

A telephone call Friday to the U.S. Embassy in Islamabad demanding a $2 million ransom for Pearl and setting a 36-hour deadline for payment also proved to be bogus.

The caller was traced and arrested Saturday in Islamabad, and police are convinced that the man was not involved in the kidnapping, the investigator said.

Police also raided an apartment in south Karachi that they think is the site from which at least some of the earlier kidnap-related e-mails were sent. The apartment, which had been rented by unidentified people for 2 1/2 months, contained computers but no residents, the investigator said.

In another significant development, the chief suspect in Pearl’s abduction may be extradited to the United States within 48 hours, according to an official in Pakistan’s Interior Ministry who spoke on condition he not be identified.

That suspect is Sheik Mubarik Ali Gilani, the man Pearl reportedly hoped to meet when he disappeared Jan. 23 in Karachi.

Gilani is a militant Islamic cleric who police say has ties to both Osama bin Laden and Richard Reid, the British national who allegedly tried to blow up an American Airlines flight with explosives hidden in his sneakers.

Police say Gilani, who heads an extremist group that allegedly has thousands of followers in the United States, operates a religious school in the Pakistan city of Lahore. Until recently, they say, he also ran several military training sites south of Lahore to prepare Islamic radicals for holy war in Kashmir, Chechnya, Afghanistan and the United States.

Among those trained at Gilani’s school and camps in Pakistan since the mid-1980s have been dozens of black American Muslims, some of whom have gone on to fight on the side of Islamic extremists in Afghanistan and elsewhere, according to police.

The plump 60-year-old militant cleric, who has made frequent trips to the United States, was arrested Thursday.

Before being flown to Karachi for further questioning, he told police he financed many of his operations in Pakistan with money sent by his followers in the United States, according to one of the arresting officers.

The officer, speaking on condition he not be identified, said Gilani warned that hundreds of his followers in the United States would react violently to his arrest.

A Pakistan government official said U.S. documents presented in support of extradition said the militant Islamic group Gilani founded, Tanzeem ul Fuqra, operates the Quranic Open University in Los Angeles, which has branches in New York City and Philadelphia.

The documents cited reports claiming that Tanzeem ul Fuqra has training compounds in New York, Michigan, South Carolina and California.