The top Republican on the Judiciary Committee accused the Obama administration of turning a blind eye to immigration enforcement, allowing "sanctuary" states and counties to decline nearly 9,000 federal detainers for illegal immigrants.

Sen. Chuck Grassley, an Iowa Republican who chairs the committee, said more than 62 percent of those detainers, or some 5,000 individuals, involved illegal immigrants who were previously charged or convicted of a crime, or presented some other public safety concern.

Nearly 1,900 of the released offenders, he noted, were arrested for another crime, including murder, after a sanctuary city or country released them.

"This is disturbing – not only to me, but to most Americans. There is no good rationale for noncooperation between the feds and state and local law enforcement," he said during a hearing he convened examining the administration's immigration enforcement policies.

"The Obama administration, in too many cases, has turned a blind eye to enforcement, even releasing thousands of criminals at its own discretion, many of whom have gone on to commit serious crimes, including murder," he added.

Grassley said he has been working on the issue for several years but the death of Kate Steinle 20 days ago at the hands of a seven-time criminal illegal immigrant sparked outrage across the country. Jim Steinle, Kate's father, who was walking arm-in-arm with her when she was shot and killed on a San Francisco pier, also testified before the committee Tuesday, calling for an act of Congress to crack down on sanctuary cities.

After she was shot, Steinle said his daughter looked at him and said, "'Help me, dad.' Those are the last words I will ever hear from my daughter."

Grassley said he recently sent Attorney General Loretta Lynch and Homeland Security Secretary Jeh Johnson a letter urging them to take control of the situation and ensure detainers are not ignored and undocumented individuals are safely transferred to federal custody and put into deportation hearings.

But he said he has yet to receive a response.

"Enforcing the immigration laws of the United States is not a voluntary or trivial matter," he said. "Real lives are at stake. Things cannot continue this way."

Grassley is working on a bill that would require state and locals to cooperate on criminal immigrants or risk losing law enforcement-related grants distributed by the Department Homeland Security and Justice Department.

The bill would require a mandatory minimum five-year prison sentence, in addition to a possible find for individuals who enter the U.S. after having been deported. Current law, he said, does not require prison time and caps the possible prison sentence at two years.

Sen. Dianne Feinstein, D-Calif., also said she is working on a bill that requires sanctuary cities and counties to cooperate with federal authorities when they ask for detainers for illegal immigrants charged or convicted of crimes.