Evelyn Rivera, 24, shows a T-shirt with a photo of her mother and sister.… (Ricardo Ramirez Buxeda…)
WASHINGTON — Evelyn Rivera was 3 years old and living in Medellin, Colombia, when her family obtained U.S. tourist visas to visit Florida.
They weren't just aiming for Disney World.
Medellin in the early 1990s was the capital of Pablo Escobar's cocaine empire, and deadly car bombs and kidnappings were rampant. So Evelyn's mother took the toddler and her 4-year-old sister on a flight to Miami with no plans to return.
"My parents wanted to make sure we were safe," said Rivera, now 24 and living in Altamonte Springs, Fla.
Their one-way trip to America is one of millions that have long frustrated U.S. authorities. The U.S. government does not check documents of everyone who exits the country, so authorities often don't know whether foreign tourists, students and workers with temporary visas ever leave.
Conventional wisdom holds that most of the estimated 11 million immigrants who are in America illegally sneaked across the southern border. But Homeland Security Department officials estimate up to 40% — or 4.4 million people — arrived on legal visas and never departed.
Foreigners entering the United States at airports and seaports are required to scan all 10 fingers in a fingerprint device and submit to a high-resolution photograph for facial recognition software. The data are shared with federal agencies for law enforcement purposes but aren't checked by immigration authorities when the visitor leaves.
Keeping track of departures may change if Congress passes the immigration law overhaul that cleared the Senate Judiciary Committee on May 21 and heads to the Senate floor for debate next month.
A provision in the bill would create a biometric tracking system that could take fingerprints, retina scans or other unique identifying data from foreign passengers boarding international flights in the nation's 30 busiest airports within six years. U.S. citizens would be exempt.
Building new departure kiosks, upgrading computer systems, buying biometric screening equipment, hiring, training and other costs could cost $7 billion, officials say.
Homeland Security Department officials say the proposed fix is unnecessary. They are already building a computerized system to check information from airline reservations — name, age, gender and other personal data — against immigration databases.
They say it is simpler, less expensive and more efficient than what the Senate bill would require. Federal authorities cross-check the data against a "no fly" list for suspects with purported terrorist links, for example.
"We have the ability now to identify, with a high degree of certainty, on a real-time basis, those who overstay the terms of their legal entry into the United States," said David Heyman, assistant secretary for policy at the Homeland Security Department.
But the system clearly has holes.
After two homemade bombs exploded during the Boston Marathon on April 15, the FBI admitted it didn't know that Tamerlan Tsarnaev, one of the two suspects, had visited the restive Caucasus region of Russia for several months in 2012. FBI agents had questioned him in 2011 after Russian intelligence warned he may have had ties to Islamic militants, but were not notified by immigration officials when he left the U.S.
Tsarnaev died in a shootout with police. His younger brother, Dzhokhar, is in custody and has been charged in the bombings, which killed three people and injured more than 260 others.
Another figure in the case, Azamat Tazhayakov, a student from Kazakhstan, was charged with conspiracy to obstruct justice for allegedly throwing away evidence he had taken from Dzhokhar's dormitory room. Tazhayakov entered the U.S. in January even though his student visa had been terminated.
The toughest departures to track are land crossings.
Canadian authorities last year began to share foreign travelers' data with U.S. officials from four border crossings — two in New York and two in Washington state — and plan to expand to the rest of the northern border this summer. U.S. officials would like similar data from the southern border, but Mexican immigration officials don't have a computer system at crossing points to collect the data.
Since 1996, Congress has ordered immigration officials to use biometric screening at land crossings. The Sept. 11 Commission recommended a similar system. But Congress has yet to appropriate the money. Enforcing biometric checks on the borders — where a majority of travelers enter and leave the United States each year — could cost $25 billion, Homeland Security Department officials say.
Some experts argue that the cost far exceeds the utility of the system.
"I remain a little skeptical about its value," said Stewart Baker, former head of policy for the Homeland Security Department.
Baker said checking biometric data as visitors leave wouldn't help immigration agents find people who stayed in the country illegally.