The mother of the brothers, ethnic Chechens from southern Russia who lived in Massachusetts, said officials in Russia, where she lives, also wouldn't accept the body.
In addition, Stefan said scores of individual offers fell through because cemeteries in their communities wouldn't take the corpse.
On Thursday, Gov. Deval Patrick called the weeklong drama to find a burial site a circus, but said he doesn't know where the site is. Patrick said he hopes attention can now return to caring for the victims of the bombing.
The family of the youngest of the three killed, 8-year-old Martin Richard, said Richard's 7-year-old sister has undergone a "milestone" 11th operation on her left leg, which she lost below the knee.
The surgery performed Wednesday on Jane Richard at Boston Children's Hospital closed the wound and will allow for the eventual fitting of a prosthesis, the family said in a statement Thursday.
The family said that because of the surgeries, infections and other complication, the girl was unable to communicate with her parents and doctors for two weeks, so she did not know at first that her brother was dead.
"There are not words to describe how hard sharing this heartbreaking news was on all of us," said the family, which was within feet of the second blast.
In Washington, Boston Police Commissioner Edward Davis told Congress on Thursday that the FBI did not initially share with Boston police the warnings from Russia's security service in 2011 about Tamerlan Tsarnaev. At the time, four city police representatives were on a federal terrorism task force.
Davis' testimony at the hearing on the government's response to the attack revealed a gap in information-sharing between federal and local officials.
The FBI closed its assessment of Tsarnaev after a cursory investigation, and Davis said that police might not have uncovered or disrupted the plot even if they had fully investigated Tsarnaev's family.
"I can't say that I would have come to a different conclusion based upon the information that was known at that particular time," he said.