Karachi, Pakistan ? With leads into Islamic extremist groups running dry, Pakistani investigators said Sunday they were expanding their search for the kidnappers of Wall Street Journal reporter Daniel Pearl into Karachi’s murky criminal underworld.

The investigation has been complicated because of several e-mails purportedly from the kidnappers which police now believe were hoaxes. Late Sunday, police searched an eastern Karachi neighborhood from which e-mails believed genuine may have been sent.

Investigators still consider Islamic extremists, especially Harkat ul-Mujahedeen, as the most likely suspects in the Jan. 23 abduction of Pearl, the newspaper’s South Asian bureau chief.

Pearl, 38, was working on a story about Islamic fundamentalists and was trying to arrange an interview with the leader of a small militant group, Sheik Mubarak Ali Shah Gilani. Pearl disappeared Jan. 23 in Karachi after leaving for an appointment at a downtown restaurant

“So far no breakthrough has been made, but some progress has been made in investigations,” Pakistani Interior Minister Moinuddin Haider said Sunday.

However, other investigators, speaking on condition of anonymity, said police still had no firm idea who was holding Pearl or where. Pakistani authorities hope for a breakthrough in the case before President Pervez Musharraf visits the United States next week.

“The various agencies of the United States government are actively trying to be helpful,” U.S. Defense Secretary Donald H. Rumsfeld said Sunday on ABC’s “This Week.” “The Pakistani government is being very cooperative and is doing what they can do.”

Condoleezza Rice, President George W. Bush’s national security adviser, also expressed satisfaction with Pakistan’s efforts to solve the case.

“We certainly hope that the kidnappers understand that they’re doing, whatever cause they are promoting, no good here, and that Daniel Pearl needs to be released and released right away,” she said on “Fox News Sunday.”

Pakistani police, however, have been unable to find two primary suspects, Mohammed Hashim and Bashir Ahmad Shabbir. Hashim, also known as Arif, is believed to be a Harkat ul-Mujahedeen activists and Shabbir was a follower of Gilani, police said.

Gilani was arrested last week, but investigators say it is uncertain whether he played any role in the abduction.

In the capital Islamabad, a top-level government task force met Sunday to review the investigation. A source who took part in the meeting said the participants discussed the possibility that the kidnapping may have been carried out by one of Karachi’s numerous criminal gangs.

The source spoke on condition of anonymity.

However, Mukhtar Ahmad Sheik, who is in charge of security here in Sindh province, confirmed that the investigation was not limited to religious extremists.

“We are keeping all options open in our investigations,” he said. “The list of suspects ranges from religious extremists to gangs of criminals.”

A number of criminal gangs – some with close ties to political and religious groups – flourish in this city of 12 million people. India claims one major gang is led by Dawood Ibrahim, suspected of bombings in several Indian cities. Pakistan denies Ibrahim is in Karachi.

Jamil Yusuf, chief of the Citizen-Police Liaison Committee, was skeptical about a criminal link. The committee was formed in the last decade to help police combat crimes, especially kidnappings.

Yusuf also said authorities have been stymied because Pearl’s abduction does not fit the pattern of most kidnappings, in which gangs routinely contact the victim’s family by telephone, which can be easily traced.

Pakistani and U.S. news media have received at least six e-mails purportedly from the kidnappers. However, police consider only two of them genuine. Those two included photos of the journalist.

Police said Sunday that a teen-age boy in the eastern border city of Lahore admitted sending two of the bogus e-mails. Authorities gave no further details except that the youth, about 15 years old, was released without charge into the custody of his parents.

Investigators, speaking on condition of anonymity, said U.S. authorities, including the FBI, were trying to trace the two e-mails believed from the kidnappers.

Late Sunday, police surrounded an apartment complex in Karachi’s eastern Gulistan-e-Jauhar neighborhood, from which they suspected the two genuine messages may have been sent.

The operation was still underway early Monday police said it would take hours to complete.

An e-mail sent to news organizations Friday claimed that Pearl had been killed and his body dumped in a Karachi cemetery. Police combed cemeteries Saturday, but found no trace of Pearl and regard the claim as a hoax.

Police said they also believed a ransom demand, telephoned to U.S. diplomats Friday, was a hoax. The caller demanded a dlrs 2 million ransom and the release of a former Taliban diplomat.

The failure to track down two primary suspects – Shabbir and Hashim – has frustrated the investigation into possible Muslim extremist links, authorities said.

Pearl had contacted both suspects in the weeks before the kidnapping, according to police. Four days before the kidnapping, Shabbir e-mailed Pearl and told him that an interview with Gilani had been arranged in Karachi, police said.

Hashim’s family has told police that they believe Hashim was killed in Afghanistan. On Sunday, Hashim’s father, Abdul Qadeer, said he did not believe his son was involved in the kidnapping “but if he is, he should immediately free the hostage and give himself up.”

“Islam and jihad (holy war) don’t allow kidnappings,” he said at his home in southern Pakistan. “The American journalist is a guest in Pakistan. It’s the responsibility of all Muslims to protect him.”

The father has been questioned, but local authorities denied he had been arrested.