Boston Marathon bombing suspect Dzhokhar Tsarnaev told authorities from his hospital bed Monday that he and his brother acted alone in last week’s attack, officials said.

CBS News correspondent Bob Orr reports that Tsarnaev, injured from the manhunt that led to his capture, is cooperating with authorities. He is communicating via writing because a gunshot wound to his neck rendered him unable to speak. Two officials also told The Associated Press that evidence indicated he and the second suspect, his brother, were motivated by religion.

On Monday Tsarneav was indicted with using a weapon of mass destruction to kill, and he could face the death penalty if convicted. A magistrate judge went to the hospital to conduct the initial appearance, an official at the Federal Courthouse in Boston confirmed to CBS News.

Tsarnaev, 19, was accused by federal prosecutors of joining with his older brother to set off the two pressure-cooker bombs that sprayed shrapnel into the crowd at the finish line last Monday, killing three people and wounding more than 180.

The criminal complaint containing the charges shed no light on the motive for the attack.

Tsarnaev was listed in serious but stable condition at Beth Israel Deaconess Medical Center, unable to speak because of a gunshot wound to the throat.

However, Tsarnaev is conscious and responding in writing to authorities, CBS News correspondent Bob Orr reported. Officials did not reveal further details on what they are asking, or what his responses are.

His brother, Tamerlan, 26, died last week in a fierce gunbattle with police.

“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,” Attorney General Eric Holder said in a statement.

The charges carry the death penalty or a prison sentence of up to life.

“He has what’s coming to him,” a wounded Kaitlynn Cates said from her hospital room. She was at the finish line when the first blast knocked her off her feet, and she suffered an injury to her lower leg.

In outlining the evidence against him in court papers, the FBI said Tsarnaev was seen on surveillance cameras putting a knapsack down on the ground near the site of the second blast and then manipulating a cellphone and lifting it to his ear.

After the first explosion went off about a block down the street and spread fear through the crowd, Tsarnaev — unlike nearly everyone around him — looked calm and quickly walked away, the FBI said. Just 10 seconds or so later, the second blast occurred where he left the knapsack, the FBI said.

The FBI did not make it clear whether authorities believe he used his cellphone to detonate one or both of the bombs or whether he was talking to someone.

The court papers also said that during the long night of crime Thursday and Friday that led to the older brother’s death and the younger one’s capture, one of the Tsarnaev brothers told a carjacking victim: “Did you hear about the Boston explosion? I did that.”

The brothers are ethnic Chechens from Russia who have lived in the U.S. for about a decade. Investigators are focusing on a trip the older brother made last year to Chechnya and Dagestan, in a region of Russia that has become a hotbed of separatist politics and Islamic extremism.

Tsarnaev was charged with using and conspiring to use a weapon of mass destruction against persons and property, resulting in death. He is also likely to face state charges in connection with the shooting death of an MIT police officer.

– CBS News