The ACLU of Massachusetts is suing the FBI and the US attorney in Boston to get more information about a federal terrorism task force based in the state, as well as that unit's investigation of a Florida man who was connected to one of the alleged Boston Marathon bombers.
The man, Ibragim Todashev, was fatally shot by representatives of the task force last May.
The lawsuit, filed Thursday in US District Court in Boston, naming the FBI and US Attorney Carmen M. Ortiz, requests records the ACLU first sought under the federal Freedom of Information Act in December, saying law enforcement agencies have refused to respond.
The lawsuit seeks documents that would explain the number and type of investigations undertaken by the task force; any records that would explain how it functions, how its duties are shared, and what oversight exists; and any information related to Todashev, who was close with the late Tamerlan Tsarnaev, one of the alleged bombers.
"We don't know much about [the task force]; it's very nebulous," said Laura Rotolo, an ACLU staff attorney.
"No one knows how it functions and who is in charge, and I think the Todashev case is an example of that," she said.
The FBI and the US attorney's office declined to comment on the lawsuit Thursday.
Todashev, a 27-year-old mixed martial arts fighter, was close with Tsarnaev, and task force agents had been asking Todashev about their relationship in the bombing inquiry.
During an interview in his Florida home, Todashev allegedly admitted he and Tsarnaev were involved in a triple homicide in Waltham in 2011.
Todashev was shot and killed following that admission after he allegedly hurled a coffee table at an FBI agent, hitting him in the head, and attempted to strike him and a Massachusetts state trooper with a metal broomstick. A Florida prosecutor and the Department of Justice ruled separately last month that the FBI agent who shot Todashev acted in self-defense, clearing the agent of any wrongdoing in the shooting.
The investigations did little to explain, however, what information, if any, Todashev may have had about the bombings, or about Tsarnaev.
The FBI and CIA have come under increasing criticism for failure to follow up on warnings that their Russian counterparts gave, as well as other signs, that Tsarnaev was increasingly veering toward radical Islam. Russian authorities provided warnings after Tsarnaev made a six-month trip in 2012 to the Russian province of Dagestan.
Tsarnaev, 26, was killed last April 19 during a confrontation with police in Watertown several days after the bombings.
His younger brother and alleged accomplice, Dzhokhar Tsarnaev, now 20, was arrested in Watertown later that day after a manhunt. He faces charges that carry the death penalty. He is being held without bail, and his lawyers have suggested in court records that they plan to argue that Tamerlan Tsarnaev was the driving force behind the bombings.
The ACLU argues in its 14-page lawsuit that the information about the joint terrorism task force is a public record, and that the information, including records about Todashev, are of public importance in light of the ongoing questions about the agency's investigations. The suit questions what role state investigators played and what oversight existed from state agencies.
"The federal government's collaboration with Massachusetts state and local police, especially through the [task force] has for years been shrouded in secrecy," the lawsuit states. "The Massachusetts [task force] conducts hundreds of investigations in Massachusetts every year, yet little is known about their structure and function."
The lawsuit notes that there is no publicly available list of agencies that participate in the task force, and there is no explanation for the chain of authority and protocols that govern local police officers when they work for the task force. The suit argues the shooting of Todashev raises major concerns.
"When law enforcement officials kill someone in his own home, the public deserves to know who was there, why and under what authority," the suit states. "But the [task force's] opacity prevents the public from getting these answers."
Milton J. Valencia can be reached at mvalencia@