Explosives residue found in slain Boston suspects's apartment

In a fresh development in the Boston Marathon bombings probe, US investigators have found explosives residue in the apartment of the slain Chechen-origin suspect Tamerlan Tsarnaev.
He is the main accused in the Boston bombings along with his 19-year-old brother Dzhokhar. Tamerlan, 26, was shot dead by police in the wee hours of April 19.
As part of the continuing probe into the attacks, investigators have found explosives residue in the apartment that Tamerlan shared with his wife and young daughter, a source briefed on the investigation has said.
The residue turned up in at least three places at the apartment in Cambridge, Massachusetts, the CNN reported.

The residue was found at the kitchen table, the kitchen sink and the bathtub, the source said.
The US authorities have arrested Dzhokhar on charges of using a weapon of mass destruction.

The two brothers allegedly carried out the deadly Boston Marathon bombings in which three people were killed and more than 250 others were injured on April 15, in one of the worst terrorist attack in the US post 9/11.
Dzhokhar also told investigators that the brothers chose to target the Boston Marathon only a day or two before the event.
Tamerlan and Dzhokhar initially planned to carry out a suicide-bomb attack on July 4, a US law enforcement official was quoted by CNN as saying.

The unnamed official said Dzhokhar told investigators their bombs were ready earlier than they expected and they decided to move up the date.
Earlier, citing unnamed officials, several media reports had said Dzhokhar told investigators that the pressure cooker bomb was made by Tamerlan inside his apartment.
"The explosives used in the Boston Marathon bombings were likely made in the Massachusetts home of suspected bomber Tamerlan Tsarnaev," Fox News reported.
After making the bombs, they drove around the city to identify the possible locations for an attack.
"They surveyed these police stations, multiple stations in Boston and one in Cambridge. They built the bombs so fast that they decided to move the whole plan up," an unnamed official was quoted by the Boston Globe as saying.

Three of Dzhokhar's friends have also been charged in connection with the case.
Azamat Tazhayakov and Dias Kadyrbayev were charged on Wednesday with conspiring to discard potentially incriminating items from Dzhokhar's dorm room. Robel Phillipos was charged with making false statements to investigators.