Here are today's top stories from The Associated Press.
FBI release images of suspects in Boston Marathon bombing; one set down a backpack
BOSTON — The FBI released photos and video Thursday of two suspects in the Boston Marathon bombing and asked for the public's help in identifying them, zeroing in on the two men on surveillance-camera footage less than three days after the deadly attack.
FBI agent Richard DesLauriers said the photos of the two men came from surveillance cameras near the explosion sites. One man is seen wearing a dark baseball cap, the other a white cap worn backwards.
The man in the white cap is seen setting down a backpack at the site of one of the blasts, DesLauriers said.
Within moments of the announcement, the FBI website crashed, perhaps because of a crush of visitors.
The images were released hours after President Barack Obama and first lady Michelle Obama attended an interfaith service at a Roman Catholic cathedral in Boston to remember the three people killed and more than 180 wounded in the twin blasts Monday at the marathon finish line.
Crews seek survivors, bodies after Texas fertilizer plant explosion; death toll is unclear
WEST, Texas — Rescuers searched the smoking remnants of a Texas farm town Thursday for survivors of a thunderous fertilizer plant explosion, gingerly checking smashed houses and apartments for anyone still trapped in debris or bodies of the dead.
Initial reports put the number of fatalities as high as 15, but later in the day, authorities backed away from any estimate and refused to elaborate. More than 160 people were hurt.
A breathtaking band of destruction extended for blocks around the West Fertilizer Co. in the small community of West. The blast shook the ground with the strength of a small earthquake and leveled dozens of homes, an apartment complex, a school and a nursing home. Its dull boom could be heard dozens of miles away from the town about 20 miles north of Waco.
Waco police Sgt. William Patrick Swanton described ongoing search-and-rescue efforts as "tedious and time-consuming," noting that crews had to shore up much of the wreckage before going in.
Searchers "have not gotten to the point of no return where they don't think that there's anybody still alive," Swanton said. He did not know how many people had been rescued.
Attorney: Man charged with mailing ricin to Obama surprised by arrest, says he is innocent
OXFORD, Miss — A Mississippi man charged with mailing ricin-tainted letters to national leaders wrote in online postings that he had uncovered a conspiracy to sell human body parts on the black market, and on Thursday his attorney said he was surprised by his arrest and maintains he is innocent.
Paul Kevin Curtis, 45, wore shackles and a Johnny Cash T-shirt Thursday in a federal courtroom. His handcuffs were taken off for the brief hearing, and he said little. He faces two charges on accusations of threatening President Barack Obama and others. If convicted, he could face up to 15 years in prison.
He did not enter a plea on the two charges. The judge said a preliminary hearing and a detention hearing are scheduled for 3 p.m. Friday.
Attorney Christi R. McCoy said Curtis "maintains 100 percent that he did not do this."
"I know Kevin, I know his family," she said. "This is a huge shock."
Gun control backers say Senate defeat won't stop them, but seem unsure about how to succeed
WASHINGTON — One day after the demise of gun control legislation, Senate supporters of the measure vowed to try again, while a leading opponent accused President Barack Obama of taking the "low road" when he harshly criticized lawmakers who voted against key provisions.
"When good and honest people have honest differences of opinion about what policies the country should pursue about gun rights ... the president of the United States should not accuse them of having no coherent arguments or of caving to the pressure," said Sen. John Cornyn, R-Texas.
The fate of the bill was sealed in a string of votes on Wednesday, when Republicans backed by a small group of rural-state Democrats rejected more extensive background checks for gun purchasers and also torpedoed proposed bans on assault weapons and high-capacity ammunition magazines.
The Senate delivered its verdict four months after a shooting at an elementary school in Newtown, Conn., left 20 first graders and six educators dead. The tragedy prompted Obama to champion an issue that Democrats had largely avoided for two decades, and that he himself ignored during his first term in the White House.
Though the gun control bill was moribund for the foreseeable future, the Senate approved two minor amendments on Thursday. One by Sen. John Barrasso, R-Wyo., cutting aid to state and local governments that release information on gun owners, was approved 67-30. Another by Sens. Tom Harkin, D-Iowa, and Lamar Alexander, R-Tenn., bolstering federal mental health programs passed 95-2.
Gun control: Everything in Obama's power turned out to be no match for gun rights advocates
WASHINGTON — President Barack Obama promised after the Sandy Hook Elementary School shooting that he'd do everything in his power to change gun laws.
Turns out his power was no match for the immovable force of gun rights advocates in Congress and across the nation.
The National Rifle Association and its energized supporters overcame the president's impassioned speeches and the national outrage over the shooting deaths of first graders. The Senate rejected new gun-buying restrictions in the face of strong public opinion, pleas from a former congresswoman still healing from bullet wounds and a billionaire bankrolling the firearms-control effort. Both sides in the debate say the NRA's power comes from gun owners who are passionate about protecting their rights.
Obama and his allies are vowing to fight on.
Senators unveil immigration bill with wide coalition of supporters as conservatives attack
WASHINGTON — Four Democratic and four Republican senators formally unveiled a sweeping immigration bill Thursday at a news conference attended by traditional opponents from big business and labor, conservative groups and liberal ones. The lawmakers argued that this time, thanks to that broad-based support, immigration overhaul legislation can succeed in Congress.
"Powerful outside forces have helped defeat certain other initiatives in Washington, but on immigration, the opposite is proving true," Sen. Chuck Schumer, D-N.Y., said a day after senators under intense lobbying pressure blocked a major gun control package. "I am confident this issue will not fall victim to the usual partisan deadlock."
Support for the bill is already being put to the test as conservatives grow more vocal in opposition. Two Republican senators held a dueling news conference with law enforcement officials to bash the bill's security provisions, and several conservative bloggers seized on one provision of the legislation to falsely claim that it would allow people here illegally to get free cellphones.
The 844-page bill is designed to secure the border, allow tens of thousands of new high- and low-skilled workers into the country while requiring employers to verify their legal status, and put 11 million people here illegally on a path to citizenship, as long as certain border security goals are met first.
"Yes, we offer a path to citizenship to people who didn't come here legally," said Sen. John McCain, R-Ariz., anticipating opposition to that provision. "They're here, and realistically there is nothing we can do to induce them all to return to their countries of origin."
Michigan woman, 75, gets at least 22 years in prison for killing teen grandson: 'I'm sorry'
PONTIAC, Mich. — A 75-year-old Detroit-area woman who killed her grandson expressed remorse Thursday but repeatedly accused his parents of dumping a troubled boy at her doorstep during a desperate, emotional plea to avoid a prison sentence that likely means death behind bars.
The judge wasn't swayed, sending Sandra Layne away for at least 22 years and capping a wrenching case that revealed family strife, adolescent rebellion and fatal consequences.
Joanthan Hoffman was shot six times, including twice in the back, last spring in Oakland County's West Bloomfield Township. Layne, a former teacher and real estate agent, said she shot him out of fear during a physical altercation, but a jury in March rejected her claim of self-defense.
Prosecutors said there were no signs of Layne being injured by Hoffman. A recording of a 911 call shows him being shot again while pleading for help — a critical piece of evidence that jurors played over and over during deliberations. Judge Denise Langford Morris zeroed in on it, too, wondering why Layne simply didn't call police if she felt helpless.
"Grandmothers are supposed to protect ... Why did you keep shooting and how could you keep shooting?" Morris asked. "You didn't have to keep shooting. Those were hollow-pointed bullets designed for a devastating impact."
Perfect planets for life? Telescope sees distant worlds not too hot, not too cold, not too big
WASHINGTON — NASA's planet-hunting telescope has discovered two planets that seem like ideal places for some sort of life to flourish. And they are just the right size and in just the right place.
One is toasty, the other nippy.
The distant duo are the best candidates for habitable planets that astronomers have found so far, said William Borucki, the chief scientist for NASA's Kepler telescope. And it's got astronomers thinking that similar planets that are just about right for life — "Goldilocks planets" — might be common in the universe.
The discoveries, published online Thursday in the journal Science, mark a milestone in the search for planets where life could exist. In the four years that Kepler has been trailing Earth's orbit, the telescope has found 122 exoplanets — planets outside our solar system.
In the past, those planets haven't fit all the criteria that would make them right for life of any kind from microbes to man.