Updated

After an exhaustive search for signs leading to Daniel Pearl proved fruitless, the Wall Street Journal is asking the missing journalist's kidnappers to show evidence that he is still alive.

"We urge (the abductors) to release Danny," read a statement prepared by Paul Steiger, the newspaper's managing editor. "If that is not possible, we call on them to demonstrate that Danny remains alive. They can do this by providing us with a photo of Danny holding today's newspaper.

"We remain eager to continue communication that will lead to Danny's release. That dialogue can be public or private. It can be direct or through a trusted intermediary. We should now resume that dialogue."

Pakistani police say that several additional arrests have been made in connection with the case, but refuse to indicate whether they have moved closer to tracking down the journalist or his kidnappers.

Those arrested include the father and other relatives of a prime suspect – a member of a Muslim extremist group whose family claimed he had recently died in Afghanistan.

Among the areas searched in an all-night effort were the 300 cemeteries of Karachi, a southern city of 12 million people.

"We have searched graveyards and other places," said police spokesman Tariq Jamil. "But so far there is no clue."

Graveyard administrators were told to prevent the burial of any bodies and to tell the police about any brought for burial by suspicious people, police said.

Pearl, 38, was kidnapped Jan. 23 in Karachi, while trying to get an interview with the founder of a militant Muslim sect. His wife, Marianne, is six months pregnant with their first child.

A caller contacted U.S. authorities Friday and demanded $2 million and the release of the former Taliban ambassador to Pakistan in exchange for the release of Pearl, senior police officials said.

But in New York, the Journal said it believed the telephone message demanding ransom money for Pearl was a hoax.

In an unsigned e-mail sent Thursday to Western and Pakistani media, the purported kidnappers said: "We will give you one more day. If America will not meet our demands, we will kill Daniel. Then this cycle will continue and no American journalist could enter Pakistan."

Authorities could not determine whether the message was sent by Pearl's captors.

On Friday, Pakistani police officials said an anonymous caller gave the Americans 36 hours to pay $2 million and free Taliban envoy Mullah Abdul Salaam Zaeef, who was arrested in Pakistan and turned over to the United States.

A State Department official said the phone call was received by the U.S. Embassy in Islamabad. Police insisted the call went to the U.S. Consulate in Karachi. There was no immediate explanation for the conflict, but a U.S. Justice Department official subsequently said the call may have been a hoax.

The first e-mail from Pearl's purported captors, sent last weekend, demanded the release of Pakistanis captured in fighting in Afghanistan and now held by the U.S. military at Guantanamo Bay, Cuba. It said Pearl would face the same "inhuman" conditions as those prisoners.

Secretary of State Colin Powell has said those demands cannot be met.

On Thursday, police said a key suspect named Arif was reported dead in southern Punjab province.

Arif is believed to be a member of Harkat ul-Mujahedeen, an Islamic extremist group with close ties to Usama bin Laden's al Qaeda network. He was reportedly one of the contacts helping Pearl set up an interview with the militant leader.

Arif's relatives were arrested Saturday at their home in southern Punjab province.

An unsigned e-mail Wednesday claimed Pearl worked for the Israeli intelligence agency, the Mossad, and set a 24-hour deadline for killing him. It also demanded all American journalists leave Pakistan within three days.

The Journal has sent repeated return e-mails denying Pearl is an agent of any government and appealing for his life.

A source close to the investigation, speaking on condition of anonymity, said Thursday's e-mail extending the deadline to kill Pearl was sent through the same server as the one received Wednesday.

The first e-mail, sent Sunday, was signed by the previously unknown National Movement for the Restoration of Pakistani Sovereignty. The message included pictures of Pearl with a pistol pointed to his head.

The Associated Press contributed to this report.