"I think what they are doing is what you expect them to do. Look at everyone and talk to everyone who has any possible information, and see what comes of it," he said. "Because of the nature of it, they're bringing in everyone."
Russell hasn't been charged with any wrongdoing and has been questioned several times by federal investigators.
She, her husband and their 3-year-old daughter had been sharing a cramped apartment in Cambridge before and after the bombings. She and the girl moved to her parents' home in North Kingstown, Rhode Island, after her husband was killed.
DeLuca said she was doing well.
"This is unnerving because they're your sisters," he said. "They're kids. They're scared stiff."
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