They are sent by police and prosecutors who hope Collins and her 11 analysts at the National Center for Missing and Exploited Children can verify that the graphic pictures are real, not computer-generated. When they can't, officials sometimes turn to outside experts.

All this is being done — at an annual cost in the millions of dollars collectively in child-pornography cases alone — as software like Photoshop makes it easier to fake photos and as juries become more skeptical about what they see.

Although challenges to digital photos come in all types of criminal and civil cases, they are especially pronounced in child-pornography cases because of a 2002 U.S. Supreme Court decision striking down a ban on computer-generated child pornography. Defense attorneys are trying to use the ruling to introduce reasonable doubt in jurors' minds about the images' authenticity.

Prosecutors still generally prevail, but "this has certainly created an additional burden," said Thomas Kerle of the Massachusetts State Police. "I can say that unequivocally, it has made the prosecution of these types of cases more difficult. It takes ... resources I think could be better applied to investigating" more cases.

Drew Oosterbaan, who heads the U.S. Department of Justice's Child Exploitation and Obscenity Section, said prosecutors sometimes submit only photos they can easily verify because outside experts can be expensive — with travel, hotels and consulting fees, along with possible delays.

"This can affect the sentence the defendant gets," he said. "Before (the 2002 ruling) we would generally charge all the images."

Oosterbaan added that although defense lawyers have the right — and duty — to challenge evidence, they are doing so without "any shred of evidence there are wholly computer-generated images being generally circulated and passed off as real children out there."

And many law-enforcement officials worry that the time and money needed to withstand any challenges will only grow as technology improves and makes it more difficult to tell a computer-generated image from a real one.

"I feel that pretty much we can tell the difference right now," said Karl Youngblood of the Alabama Bureau of Investigation. "How much longer that's going to last, I don't know with the technology going at the rate it's going."

Of course, there's a cost to defendants as well — sometimes more so because federal law limits where and when the defense may review images to restrict their distribution, meaning experts must often travel with expensive equipment to a police lab in another city.

"If something becomes more difficult for the government to prove, so be it. They have the burden of proof," said First Amendment lawyer Louis Sirkin, lead counsel in the challenge that led to the 2002 Supreme Court ruling.

Child pornography is illegal in the United States, but the Supreme Court in 2002 struck down on free-speech grounds a 1996 federal ban on material that "appears to be" a child in a sexually explicit situation. That ruling covers computer-generated images, though morphing — such as the grafting of a child's school picture onto a naked body — remains illegal.

Collins' Child Victim Identification Program in Alexandria, Va., grew out of that ruling. After officials submit seized photos, the center uses software and visual inspections to look for matches. It can usually verify that children in some or all of the images are known and real.

The program, which costs about $1 million a year to run, now has about 1,300 children in its database, up from 20 in 2002. Staff grew from just Collins then to 11 full-time analysts who now work under her. The program reviewed 5 million images last year, up from about 450,000 in 2003, the program's first full year.

Because of the graphic nature of the images, a psychologist visits each week, and analysts must undergo counseling at least quarterly.

"Not everybody can do it," said Raymond Smith, a longtime investigator who oversees child-exploitation cases at the U.S. Postal Inspection Service. "You have to be able to come to grips with seeing children be victimized and abused. It can tear you up, (but) through your efforts you are identifying the people that hurt these children."

When the center cannot make a match, prosecutors can turn to outside experts. Sometimes, it's a pediatrician who can say a real child has characteristics matching those seen in the photo. Other times it's a computer expert who can talk about how difficult it is to produce images and video of that quality.

Hany Farid, a Dartmouth College professor who has testified for the prosecution in some cases, said he has been getting more inquiries about authenticity — not only for child-pornography cases but also civil lawsuits questioning medical images in malpractice cases or signatures in contract disputes. News organizations have also looking for ways to authenticate photos.

"Because so many people get photographic fakes in their (electronic) mailboxes, to the average juror it resonates," he said.

The challenges can be costly, even if a case never goes to trial — the majority end in plea agreements.

Farid said he charges up to $25,000 a year for software he produced to look for signs of tampering, such as inconsistencies in shadows. He also charges as much as tens of thousands of dollars to work on a case.

Even when there is a match and an expert isn't needed, a prosecutor must seek out the detective who initially identified a child for the center. That detective must often be flown in and be ready to testify if the defense raises a challenge. In one case in Portland, Maine, a Russian detective couldn't be reached, so the prosecutor had to spend $5,000 on an expert anyway. Trials get postponed if a key witness has a scheduling conflict.

Sam Guiberson, a defense attorney who specializes in technology and digital evidence, said challenges to evidence are to be expected, digital or not.

"Every good trial lawyer is always going to subject every part of his adversary's exhibits to that sort of scrutiny," Guiberson said.

Kebin Haller, deputy director of the Wyoming Division of Criminal Investigation, said that in most cases, a large quantity of images are seized such that enough hold up.

How much proof a prosecutor needs in child-pornography cases can vary from region to region and even from judge to judge. Recent federal appellate rulings have eased the burden on prosecutors, essentially saying that in lieu of definitive evidence, they can let jurors make up their own minds about whether an image is real or computer-generated.

Many prosecutors, though, don't want to take that chance and would rather submit proof.

"It's difficult to prove these are real children," said Mary Leary, a Catholic University law professor who previously worked on child-abuse and child-pornography cases. "Is the defense exploiting this? Absolutely they are."

The state argued that a 1934 federal law prevents the government from taking land into trust for tribes recognized after the law took effect, unless Congress specifically authorized it. The Narragansetts became a federally recognized tribe in 1983.

The 1st U.S. Circuit Court of Appeals in Boston rejected the state's claim.

At issue is whether a 31-acre lot in Charlestown purchased by the Narragansetts should be subject to Rhode Island law, including a prohibition on casino gambling, or whether the parcel should be governed by tribal and federal law.

The dispute dates to 1991, when the Narragansetts purchased the land to build an elderly housing complex, which remains incomplete.

The state objected when the tribe asked the U.S. Department of the Interior to take the land into federal trust, which would place it largely under tribal and federal control.

The justices declined to examine a trial procedure in which a jury first determines whether smokers as a group are entitled to punitive damages before establishing whether any single smoker is entitled to compensation.

Later, a new jury addresses issues unique to each alleged smoking victim who sued.

West Virginia courts are allowing the approach, which has been used in other types of lawsuits, including claims for asbestos exposure.

The second phases of such trials rarely occur, because the two sides usually settle once they know the value of the case.

Tobacco companies oppose use of the legal device, which lawyers call "reverse bifurcation."

The tobacco industry said a jury doesn't know until later in a case whether any smoker was actually harmed or how serious any injury was; which defendants if any were responsible; or the amount of compensatory damages any defendant owes to smokers.

In addition to helping resolve suits over asbestos exposure, reverse bifurcation has been applied to claims against makers of the dangerous diet drug fen-phen.

In asking the justices not to take the case, lawyers for the smokers said further delay would mean that most of their clients would die before their cases could be tried, "thus affording the defendants a free pass" for their alleged misconduct.

The smokers say the companies secretly agreed not to market a truly safer cigarette while publicly proclaiming the safety of their own particular brands.

The first phase of the trial was scheduled to begin March 18.

The businessman, Kazuyoshi Miura, was arrested Friday in the U.S. territory of Saipan as he tried to pass through immigration control at the airport to take a flight home. Miura, 60, was convicted in Japan in 1994 of killing his wife, Kazumi Miura, but the verdict was overturned 10 years ago.

"Given that this case has been closed in Japan, the Justice Ministry and Japanese police should no longer have to respond to requests from the police for evidence or to cooperate with the investigation," said Miuri's lawyer, Shinichiro Hironaka.

Miura and his wife were visiting Los Angeles on Nov. 18, 1981, when they were shot in a parking lot. Miura was hit in the right leg, while his 28-year-old wife was shot in the head. The shooting caused an international uproar, in part because he blamed the attack on robbers, reinforcing Japanese perceptions of America as violent.

The arrest came after cold-case detectives from the Los Angeles Police Department worked with authorities in Saipan and in Guam, police said in a statement. Police did not make details on the arrest available.

At a bail hearing Monday in Saipan, Miura told the court the killing "took place several decades ago, and it is unlikely that I will destroy evidence or run away," according to the Kyodo News Agency.

The court, however, denied him bail. A preliminary hearing was set for March 5, said Rosie Ada, deputy clerk at Superior Court. An arraignment was also slated for March 10, she said.

Sean Bell, who had been spending his last night as a single man partying, was killed in a barrage of 50 police bullets outside a strip club.

The three police officers indicted in the shooting were to go on trial Monday in a case that has sparked protests and debate over excessive force and police conduct in New York City.

Bell's fiancee was expected to be the first witness at the trial, and she has said she plans to be in court every day.

"I feel like I need to know. I need to know why this happened," said Paultre Bell, who had her maiden name legally changed after her fiance's death. "I wake up one day and my world is turned upside down. I have to know why this happened; my family deserves to know."

Sean Bell, 23, was killed Nov. 25, 2006, hours before he was to marry the mother of his two children. He and two friends were confronted by undercover officers investigating reports of drugs and prostitution.

Detective Michael Oliver fired 31 shots, including the one that killed Bell. Detective Gescard Isnora squeezed off 11 rounds, and Detective Marc Cooper fired four times. Oliver and Isnora have pleaded not guilty to manslaughter; Cooper has pleaded not guilty to reckless endangerment.

Police union officials and defense lawyers have said the detectives believed Bell and his friends were going to get a gun, though no weapon was found. The officers opened fire after the car the three men were in lurched forward, bumped Isnora and slammed into an unmarked police minivan, authorities said.

After years in Fidel's charismatic shadow as Cuba's number two and defense minister, Raul Castro faces massive challenges, including preparing the transition of power to a newer generation and reforming the economy.

"Fidel is irreplaceable; the people will continue his work when he is no longer with us physically, though his ideas always will be here," Raul Castro, 76, told lawmakers in his acceptance speech late Sunday.

In the 19 months since he took over as temporary leader, Raul Castro has made some minor adjustments in the economy, while promising bigger changes.

But he has made it clear that everything will take place "within socialism" and that solutions to the country's problems will come "little by little."

People in the street voiced hopes that the new president would usher in long-sought economic reforms to improve their daily lives.

"This is the best that could have happened to Cuba," Carlos Muguercia, a 78-year-old craftsman said. "Raul already knows the situation. He knows how to solve problems, in any case the most serious ones."

Others were less enthusiastic at the dynastic succession.

"Raul is Fidel without a beard," argued one young man enjoying a beer at a bar in Havana's historic center.

In a sign that change may take time, Raul Castro said he would consult with his brother on major issues. And he vowed to be on guard against Cuba's powerful northern neighbor the United States.