Members of Congress yesterday threatened sanctions against Mexico for failing to extradite scores of criminals wanted in the United States on drug trafficking and murder charges.

The congressional anger was unleashed by an emotional hearing on the 1997 murder of Sheila Bellush, a 35-year-old Sarasota, Fla., woman who was shot in the face and slashed across the throat in front of her 2-year-old quadruplets. The alleged killer, Jose Del Toro Jr., was arrested in Mexico a few days later and is waging a legal battle against extradition.

"Why isn't Del Toro sitting on death row in Florida? Why has my family been subject to continued anguish and denied justice?" demanded the victim's husband, James J. Bellush, as video monitors showed pictures of his wife's mutilated body. "Because Mr. Del Toro, who is an American citizen, who murdered another American citizen on American soil, crossed the border into Mexico. Mexico has decided to interfere with the American justice system and allowed Del Toro to appeal his extradition all the way to the Mexican supreme court."

Extraditions have long been a bone of contention in U.S.-Mexican relations. U.S. officials said 275 extradition requests are pending with Mexico, which has approved only 42 since 1996. Of those, 20 were on drug charges, only one was a Mexican citizen, and none have been Mexican drug kingpins.

"The hearing was to see if Mexico is a safe haven for drug traffickers and criminals," said Rep. John L. Mica, (R-Fla.), who chaired the session before a subcommittee of the Government Reform Committee. "Unfortunately today the question has to be answered in the affirmative."

Visibly moved by Bellush's testimony, Mica and other members of the subcommittee on criminal justice, drug policy and human resources said they would pursue every avenue available to pressure Mexico to hand over Del Toro. Among the possible measures, they said, are using U.S. influence to block loans for Mexico by the World Bank and International Monetary Fund.

Mexican officials said they could not simply deport Del Toro because he entered Mexico legally. They also said they must allow their legal system to process the extradition request, even if it takes longer than they would like.

"And as soon as a country puts out an arrest warrant, you can't deport the person, you have to arrest them," said a Mexican official.

Mary Lee Warren, a deputy assistant attorney general, said she asked the Mexicans to investigate who was paying Del Toro's legal bills because he had few known financial resources.

Neither Mexican nor U.S. officials were able to provide the names of Del Toro's attorneys yesterday. He has not yet had to enter a plea in court.

After a heated exchange with Warren and other administration officials, Mica said another hearing would be called for August and warned that if necessary, subpoenas could be issued to Attorney General Janet Reno and Secretary of State Madeleine K. Albright to explain why more pressure is not being applied to Mexico to resolve the Del Toro case.

"This is a very important test, because if we can't [extradite] under these conditions, when will we be able to do it?" asked Rep. Elijah E. Cummings (D-Md).

CAPTION: Sheila Bellush, here with husband James J. Bellush and their quadruplets, was murdered in 1997 as her children watched. James Bellush testified at the Hill hearing.

CAPTION: Jose Luis Del Toro Jr. is in Mexico fighting extradition for Sarasota, Fla., slaying.