Boston bombing traced to pressure cookers

BOSTON - Federal agents zeroed in Tuesday on how the Boston Marathon bombing was carried out - with kitchen pressure cookers packed with explosives, nails and other lethal shrapnel - but said they still didn't know who did it and why.

An intelligence bulletin issued to law enforcement and released late Tuesday included a picture of a mangled pressure cooker and a torn black bag the FBI said were part of a bomb.

The FBI and other law enforcement agencies repeatedly pleaded for members of the public to come forward with photos, videos or anything suspicious they might have seen or heard.

"The range of suspects and motives remains wide open," Richard DesLauriers, FBI agent in charge in Boston, said at a news conference. He vowed to "go to the ends of the Earth to identify the subject or subjects who are responsible for this despicable crime."

Spirited 8-year-old identified as victim in Boston

BOSTON - Third-grader Martin Richard had just gotten ice cream and was near the Boston Marathon finish line, eagerly watching for friends to run by. Krystle Campbell was enjoying the race with her best friend, hoping to get a photo of the other woman's boyfriend after he conquered the last mile.

Then the unthinkable struck. The spirited 8-year-old, pictured on Facebook in his classroom holding a sign that read "No more hurting people," was dead, along with the outgoing 29-year-old woman and a graduate student from China - victims of twin bombs that turned a scene of celebration into chaos.

More than 170 otherssuffered injuries that included severed limbs, shrapnel wounds, broken bones and head trauma.

Jeff Bauman Jr., a man pictured in an Associated Press photo being rushed from the scene Monday in a wheelchair, lost both legs. Rescuers took the 27-year-old to Boston Medical Center, where doctors found extensive vascular and bone damage.

Letter sent to senator tests positive for ricin

WASHINGTON - An envelope addressed to Sen. Roger Wicker of Mississippi twice tested positive Tuesday for ricin, a potentially fatal poison, congressional officials said, heightening concerns about terrorism a day after a bombing killed three and left more than 170 injured at the Boston Marathon.

One senator, Claire McCaskill of Missouri, said authorities have a suspect in the fast-moving ricin case, but she did not say if an arrest had been made. She added the letter was from an individual who frequently writes lawmakers.

On Tuesday night, FBI spokesman Paul Bresson said initial field tests on the substance produced mixed results and that it is in the process of undergoing further analysis at an accredited laboratory. Only after that testing can a determination be made about whether the substance is ricin, Bresson said.

The U.S. Capitol Police, which is also investigating the case, declined to comment.

Late Tuesday, Wicker released a statement acknowledging the letter and said it was sent to his Washington office.

Senate plans gun control votes today

WASHINGTON - The Senate set a long-awaited vote for today on a bipartisan plan for expanding background checks to more firearms buyers, with supporters facing a steeply uphill path to victory.

By scheduling the roll call, Senate leaders ensured a showdown over the cornerstone of an effort by gun control supporters to tighten firearms laws following December's killings of 20 students and six aides at an elementary school in Newtown, Conn.

The Senate planned to vote on eight other amendments as well to a Democratic gun control bill that besides expanding background checks, would tighten laws against gun trafficking and boost school safety aid.

They included Democratic proposals to ban assault weapons and high-capacity ammunition clips, which are expected to lose; a Republican proposal requiring states to honor other states' permits allowing concealed weapons, which faces a close vote; and a broad GOP substitute for the overall gun measure.

The focus of both sides has been on a compromise by Sens. Joe Manchin, D-W.Va., and Patrick Toomey, R-Pa., broadening background checks. It will be the first amendment voted on Wednesday. Despite appearances at the Capitol on Wednesday by wounded former Rep. Gabrielle Giffords, proponents seem to face enough potential opponents to derail their endeavor unless they can figure out how to win more votes.

Immigration bill draws criticism from left, right

WASHINGTON - To some conservatives, it's amnesty.

To some immigration advocates, it's unnecessarily punitive.

The Senate's new bipartisan immigration bill drew criticism from the right and from the left Tuesday - convincing members of the bipartisan "Gang of Eight" who wrote it that they're on the right track.

"This has something for everybody to hate," said Sen. Jeff Flake, R-Ariz.

Said Sen. Chuck Schumer, D-N.Y.: "No one gets everything they want."

Chavez heir: U.S. cause of post-election violence

CARACAS, Venezuela - President-elect Nicolas Maduro and his opposition rival traded accusations Tuesday over blame for post-election violence that the government said had caused seven deaths and 61 injuries across Venezuela.

Maduro accused the U.S. of fomenting the violence, which appeared less serious than he suggested, while opposition candidate Henrique Capriles accused him of creating a smoke screen to divert attention from the opposition's insistence on a vote-by-vote recount of Sunday's surprisingly close vote.

In Washington, the U.S. State Department backed that demand, saying it would not recognize Maduro without a recount. It was joined by the governments of Panama and Paraguay.

Maduro, the chosen heir of the late Hugo Chavez, spent the day on state TV at various events demonizing Capriles as "a murderer" and coup plotter. He also heaped blame on Washington - always a popular target of Chavez, the leader Maduro served as foreign minister for six years.

"The (U.S.) embassy has financed and led all these violent acts," Maduro said during a televised meeting at the headquarters of the state oil company.

- Associated Press