WASHINGTON — A senior Republican senator said Friday that the approaching political debate about an immigration overhaul should take into account the revelation that the suspects in the Boston Marathon bombing had apparently immigrated to the United States from the former Soviet Union.
Senator Charles E. Grassley of Iowa, the most senior Republican on the Senate Judiciary Committee, opened a hearing on immigration legislation by stressing that the issue was important ‘‘particularly in light of all that’s happening in Massachusetts right now and over the last week.’’
‘‘Given the events of this week, it’s important for us to understand the gaps and loopholes in our immigration system,’’ Grassley said in his opening statement. ‘‘While we don’t yet know the immigration status of people who have terrorized the communities in Massachusetts, when we find out it will help shed light on the weaknesses of our system.’’
Friday’s hearing was expected to offer an early glimpse into how Democrats and Republicans in the Senate would react to immigration legislation that a bipartisan group of senators introduced this week.
Instead, it was overshadowed by developments in the Boston bombing case, which also affected the meeting directly, as Homeland Security Secretary Janet Napolitano, who was scheduled to testify before the committee on border security and enforcement, had to cancel her appearance at the last minute to oversee the department’s involvement in the investigation.
A senior US official briefed on the government’s investigation Friday told The Boston Globe that bombing suspect Dzhokhar Tsarnaev, now 19, and his father and mother were issued visas to come to the United States in the Kyrygz capital of Bishkek in 2002 and arrived in Boston later that year.
The father then applied for refugee asylum status through the Department of Homeland Security, claiming the mother and son as dependents.
The Department of Homeland Security did not respond to a request for more details about the family’s asylum application, including why they specifically claimed they could not remain safe in Kyrgyzstan.
The older son and the other bombing suspect, Tamerlan Tsarnaev, 26, who was killed in a shootout with police Thursday night, was a teenager when his parents and younger brother came to the United States and remained in Kyrgyzstan with his two sisters until the following year when his father sought permission to bring them to the United States to reunify the family.
Last year the father, mother, and youngest son became US citizens, said the official, who was not authorized to speak to the press. The older brother, who had not been in the country as long as the others, had not earned American citizenship. He did not know the citizenship status of the sisters.
‘‘How can individuals evade authorities and plan such attacks on our soil?’’ Grassley asked. ‘‘How can we beef up security checks on people who wish to enter the US?’’
Senator Charles E. Schumer, Democrat of New York, a member of the bipartisan group behind the legislation, urged caution about linking the bombings to flaws in the country’s immigration system.
‘‘Before I get to the bill, I’d like to ask that all of us not jump to conclusions regarding the events in Boston, or try to conflate those events with this legislation,’’ Schumer said.
Referring to the legal immigration program through which the brothers most likely came to the country, Schumer added: ‘‘In addition, both the refugee program and the asylum program have been significantly strengthened in the past five years, such that we are much more careful about screening people and determining who should and should not be coming into the country.’’
The hearing formally kicked off consideration of a plan that would increase border security and would quickly legalize many of the 11 million unauthorized workers in the United States, eventually offering them a path to full citizenship.
Opponents of the plan and conservative pundits had already begun citing the Boston bombings as a reason to move slowly.