Massachusetts State Police colonel Timothy Alben on Saturday said no positive result had been reached in the Boston bombings case, adding the police went through 20 streets to ensure safety of the citizens.
Massachusetts governor Deval Patrick said a stay-in-place order for Boston has been lifted and mass transit reopened on Friday afternoon while police pressed ahead with a manhunt for the second suspect in the Boston Marathon bombing.
Timothy Alben told reporters at a joint press conference that authorities are committed to seeing resolution of the Boston Marathon bombing case.
Alben said there was no direct evidence that the suspect at large remains in Boston, although he is believed to still be in Massachusetts.
US President Barack Obama called Deval Patrick and Boston mayor Thomas Menino on Friday to offer ongoing federal help in the Boston bombing investigation, and to express condolences for a police officer killed in the search for suspects.
"The President said that the entire country is behind the people of Boston as well as Massachusetts, and that the full force of the federal government will continue to be made available until those responsible are brought to justice," a White House official said.
Obama stayed out of the public eye on Friday after traveling to Boston on Thursday to speak at a service for the victims of Monday's bombing.
Top White House officials continue to watch the situation and brief Obama, the White House said.
Two brothers, one now dead, one alive and at large. Hours after the first grainy images of them were released to the public by the FBI, a portrait quickly emerged Friday of the young men suspected in Monday's deadly Boston Marathon bombing.
Stunned friends pleaded for the surviving brother, 19-year-old Dzhokhar Tsarnaev, described as bright and outgoing, to turn himself in and not hurt anyone. Classmates reported seeing him on his university campus after the attacks, looking calm.
His older brother Tamerlan, a talented boxer who is said to have a wife and young daughter, was believed to be 26 when he was killed overnight in a shootout with police.
"I don't have a single American friend. I don't understand them," he was quoted as saying in a photo package that appeared in a Boston University student magazine in 2010. Relatives said he struggled to find himself in the US.