* Younger suspect returned to college campus after blasts
* Neither suspect licensed to own guns where they lived
* U.S. prosecutor known for aggressive record (Adds details on memorial services, prosecutor, guns)
By Scott Malone
BOSTON, April 22 (Reuters) - The badly wounded Boston Marathon bombing suspect faced federal charges as early as Monday and the city of Boston planned tributes to the dead after a week of blasts, shootouts, lockdowns and one of the largest manhunts in U.S. history.
Dzhokhar Tsarnaev, 19, an ethnic Chechen college student suspected of carrying out the attacks with his older brother, lay in a Boston hospital under armed guard. He was unable to speak after he was captured with throat injuries sustained during shoot-outs with police.
Police declined to comment on media reports he was communicating with authorities in writing.
"There have been widely published reports that he is (communicating silently). I wouldn't dispute that, but I don't have any specific information on that myself," Boston Police Commissioner Ed Davis told CNN. "We're very anxious to talk to him and the investigators will be doing that as soon as possible."
The FBI said on Monday morning that Tsarnaev remained in serious condition at Beth Israel Deaconess Medical Center.
Tsarnaev's capture on Friday night ended a manhunt that virtually shut down greater Boston for some 20 hours. His older brother, Tamerlan Tsarnaev, 26, died after a gunfight with police early Friday morning.
The city of Boston crawled back to normal on Monday, a week after twin bombs exploded at the crowded finish line of the city's famous marathon road race, killing three people and wounding 176. Ten of the injured lost limbs.
The crime scene around the blasts was still closed but was expected to reopen within a day or two. Signs declaring "Boston Strong" hung about the city.
Memorial services were set on Monday for two of those killed in the bombings: Krystle Campbell, a 29-year-old restaurant manager, and Chinese graduate student Lingzi Lu.
An 8-year-old boy, Martin Richard, was also killed.
PAUSE AT TIME OF BOMBINGS
The city also planned to pause at 2:50 p.m. (1850 GMT) to mark the moment a week ago when the two bombs made of pressure cookers and packed with nails and ball bearings tore through the crowd watching runners complete the Boston Marathon.
In the days that followed, investigators examining thousands of images from surveillance video, media coverage and spectators taking pictures were able to pick out two men as suspects, later identified as the Tsarnaev brothers.
On Tuesday, the day after the attack, the younger Tsarnaev was working out in the gym at the University of Massachusetts-Dartmouth, listening to music on his iPod, when he struck up a conversation with fellow sophomore Zach Bettencourt.
Bettencourt said he and Tsarnaev chatted about the bombings.
"It's crazy this is happening now," Bettencourt recalled Tsarnaev telling him. "This (these bombings) is so easy to do. These tragedies happen all the time in Afghanistan and Iraq."
Police said the Tsarnaev brothers made enough additional bombs for them to believe that more attacks were planned. They were also armed with handguns. A shootout with police in the Boston suburb of Watertown early Friday morning left more than 200 spent shell casings in the street.
Neither Tsarnaev brother was licensed to own guns in the towns where they lived, Cambridge, Massachusetts, authorities said on Sunday.
Dzhokhar Tsarnaev could be charged with several crimes including use of weapons of mass destruction, terrorism and bombing of places of public use in addition to homicide, said former federal prosecutor and University of Notre Dame law professor Jimmy Gurul?.
Because death resulted, each statute authorizes the death penalty, he said.
Though the case is likely to involve officials at the highest levels including Attorney General Eric Holder, the prosecutor in charge will be Carmen Ortiz, the U.S. attorney for the district of Massachusetts.
Ortiz has faced criticism for coming down too hard on some defendants, but that approach may become a legal asset for the biggest case of her career, said attorneys who have faced off against her.
The Tsarnaev brothers emigrated to the United States a decade ago from Dagestan, a predominantly Muslim region in Russia's Caucasus. The men's parents, who moved back to southern Russia some time ago, have said their sons were framed.
Much of investigators' attention has focused on a trip to Russia last year by Tamerlan Tsarnaev, and whether he became involved with or was influenced by Chechen separatists or Islamist extremists there.
Tamerlan Tsarnaev traveled to Moscow in January 2012 and spent six months in Dagestan, a law enforcement source said. Neighbors in Makhachkala, the region's capital city, said he kept a low profile while visiting there last summer, helping his father renovate an apartment unit. [ID: nL5N0D80EL].
That trip, combined with Russian interest in Tamerlan communicated to U.S. authorities and an FBI interview of him in 2011, have raised questions whether danger signals were missed.
(Additional reporting by Jonathan Allen, Mary Ellen Clark, Ross Kerber and Hillary Russ; Writing by Daniel Trotta; Editing by Phil Barbara and Frances Kerry)