In the days since the suspects were identified last week, a picture has emerged of 26-year-old Tamerlan Tsarnaev — the elder of the two brothers, who was killed Friday in the battle with police — as an increasingly militant immigrant, whom family members described as unhappy and mean.

His brother Dzhokhar, 19, captured Friday night, is in serious condition and under heavy guard at Beth Israel Deaconess Medical Center. He has a gunshot wound to his throat, said US Senator Dan Coats, a Republican on the Select Intelligence Committee, on ABC’s “This Week.’’

New details on the brothers’ fight with police suggests Tamerlan was killed when his brother ran him over, dragging Tamerlan underneath his car in his bid to escape.

In disrupting the talk in January at the Islamic Society of Boston mosque in Cambridge, Tamerlan Tsarnaev’s shouted at a speaker: “You are a Kafir” – a nonbeliever, according to Yusufi Vali, a spokesman for the mosque. Tsarnaev went on to say the speaker was contaminating people’s minds, and accused him of being a hypocrite.

The congregation disagreed, according to Vali, and “shouted him out of the mosque” on Prospect Street.

Tsarnaev also interrupted a talk last November when a speaker said it was fine for people to celebrate holidays such as Thanksgiving and July 4, in the same way you celebrate the birthday of the Prophet. Tsarnaev challenged him and the two talked after service. “The brother was angry, but he left,’’ Vali said.

Authorities believe the Tsarnaev brothers planted two crude bombs made from pressure cookers near the finish line of the Boston Marathon last Monday, killing three and wounding more than 170. Fifty-two victims remained hospitalized Sunday at Boston hospitals; four were in critical condition.

On Sunday, as government and law enforcement officials appeared on talk shows, the victims of the attacks were mourned in churches around the region, as pastors and priests tried to help people understand the week of violent mayhem.

Residents and businesses near the sites of the bomb blasts in the Back Bay remained barred from their buildings, but the city laid out a timeframe for their return, possibly within the next two days.

School districts around the region prepared for students to return to classes on Monday, and to help them confront any questions or fears they might have, while the family of Krystle Campbell, who was killed in the blast, prepared to bury their daughter.

Boston Police Commissioner Edward Davis said Sunday that federal authorities are trying to trace the origin of the firearms and explosive devices used by the suspects. “We hope to try to find out exactly where they obtained” the arsenal, he said.

‘‘We have reason to believe, based upon the evidence that was found at that scene — the explosions, the explosive ordnance that was unexploded, and the firepower that they had — that they were going to attack other individuals,” Davis told CBS News’s ‘‘Face the Nation.’’

Asked about any further threat to the public, Governor Deval Patrick, also appearing on “Face the Nation,’’ said “all of law enforcement feels it is over. . . . You can feel the relief here at home.”

On NBC’s “Meet the Press,’’ Patrick said surveillance video showed Dzhokhar Tsarnaev dropping a backpack, believed to have contained a bomb, and walking away shortly before the second of two explosions, 12 seconds apart, boomed on Boylston Street.

‘‘It does seem to be pretty clear that this suspect took the backpack off, put it down, did not react when the first explosion went off, and then moved away from the backpack in time for the second explosion,’’ Patrick said. ‘‘It’s pretty clear about his involvement and pretty chilling, frankly.’’

The new details on the bombing come as lawmakers in Washington, including Senator Lindsey Graham, a Republican of South Carolina, are turning up the heat on the FBI over the bureau’s handling of Tamerlan Tsarnaev, whom the department investigated and interviewed in 2011 after Russian authorities suggested he may have links to radical groups. The FBI did not find any evidence he was involved in terrorism.