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Tsarnaev also is likely to face state charges in connection with the fatal shooting of Massachusetts Institute of Technology Police Officer Sean A. Collier, 26, who was shot in his cruiser during the suspected bombers’ desperate attempt to flee.

The charging documents said a preliminary examination of the remains of the explosive devices used in the marathon bombing revealed that they were low-grade explosives housed in pressure cookers that also contained ball bearings and nails. It said many of the BBs were contained within an adhesive material and the explosives had green-colored hobby fuses.

Devices later discovered at the scene of the police shootout were constructed similarly.

The documents also said one of the bombers told a carjacking victim, “Did you hear about the Boston explosion? I did that.” At that point, the affidavit said, one of the bombers showed the driver a loaded gun and told him, “I am serious.”

Authorities have described the brothers as ethnic Chechens from Russia who have lived in the U.S. for about 10 years. Authorities have looked into a trip the elder brother took last year to Chechnya and Dagestan, in a region of Russia that has become a hotbed of Islamic extremism.

Late Monday, The Associated Press, citing anonymous sources, said evidence from an interrogation suggests the brothers were motivated by their religious views, but there was no evidence of ties to specific Islamic terrorist groups.

Tsarnaev is specifically charged with one count of using and conspiring to use a weapon of mass destruction an improvised explosive device or IED against persons and property within the United States resulting in death, and one count of malicious destruction of property by means of an explosive device resulting in death. The statutory charges authorize a penalty, upon conviction, of death or imprisonment for life or any term of years. Tsarnaev had his initial court appearance Monday in his hospital room, and several news organizations reported later that the 19-year-old was read his Miranda rights.

“Although our investigation is ongoing, today’s charges bring a successful end to a tragic week for the city of Boston, and for our country,” said Attorney General Eric H. Holder Jr. “Our thoughts and prayers remain with each of the bombing victims and brave law enforcement professionals who lost their lives or suffered serious injuries as a result of this week’s senseless violence.”

U.S. Attorney Carmen Ortiz, whose office will prosecute the case, called the charges the “culmination of extraordinary law enforcement coordination and the tireless efforts of so many, including ordinary citizens who became heroes as they responded to the call for help in the hours and days following the marathon tragedy.”

“The impact of these crimes has been far-reaching, affecting a worldwide community that is looking for peace and justice,” Ms. Ortiz said. “We hope that this prosecution will bring some small measure of comfort both to the public at large and to the victims and their families that justice will be served.”

Much work remains

Col. Timothy P. Alben, superintendent of the Massachusetts State Police, said that while Friday night’s capture of the suspect brought immediate relief to a community from a public safety viewpoint, much work remains and many questions require answers.

“Today’s charges represent another step on the long road toward justice for the victims of these crimes,” he said.

On Sunday, hundreds attended a Mass at St. Ann Catholic Church in Dorchester, Mass., for Martin Richard, the 8-year-old boy who was killed in the attack. On Monday night, Boston University students and faculty members gathered at a service for Lu Lingzi, 23, the Chinese graduate student who died in the bombing. Later this week, MIT will remember Officer Collier.

The case is being prosecuted by Assistant U.S. Attorneys William Weinreb and Aloke Chakravarty from the Anti-Terrorism and National Security Unit of the U.S. Attorney’s Office in Boston, with assistance from the Counterterrorism Section of the Justice Department’s National Security Division.