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.

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 criminal gangs.

A number of criminal gangs some with close ties to political and religious groups flourish in this city of 12 million people.

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, calls that 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.

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.

The discovery in Karachi of a light-skinned man in his late 30s led to initial media reports Sunday that the body was Pearl’s, but police said the corpse was that of an Iranian.

“We continue to believe that Danny is alive,” said Steve Goldstein, a vice president of Dow Jones & Co., the Journal’s owner.

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