LOS ANGELES >> U.S. immigration agents cannot effectively track foreigners who overstay their visas because of outdated technology involving numerous computer systems and a lack of screening when visitors leave the country, according to a government watchdog report released today.

Agents and analysts must use 10 to 40 passwords to access the computer systems, said the report by the U.S. Department of Homeland Security’s Office of Inspector General.

The inefficient computer systems plus insufficient technology training for agents hampers their ability to monitor the immigration status and whereabouts of visa holders who travel to the U.S., the report said.

U.S. Immigration and Customs Enforcement agents have been locked out of computer systems for periods ranging from several minutes to days and some keep their passwords written out on their desks, creating a security risk, the report said.

“As a result, it may take months for ICE to determine a visa holder’s status and whether that person may pose a national security threat,” the inspector general’s office said.

Visitors are screened when they enter the U.S. but the government has been slow to develop an effective system that will keep track them and their status when they leave, the report said.

The problems can be frustrating and waste agents’ time, said Claude Arnold, a former special agent-in-charge for ICE’s homeland security investigations in Los Angeles.

“They take all the time to run a bunch of other databases to locate the person. They go out and knock on doors,” he said. “And then, they go to the last place of residence, and they knock on the door, and ‘Oh, that person left the country.’”

More than 500,000 foreigners who entered the U.S. during a one-year period ending in September 2015 overstayed their visas, the report said.

The U.S. government has launched a biometric exit screening pilot program for visa holders at Atlanta’s Hartsfield-Jackson International Airport and plans to expand it to other airports in 2018.

Under the pilot program, U.S. Customs and Border Protection combined traveler and airline data with images taken of passengers to confirm their departure, the report said.

The biometric screening exit system was a recommendation of the federal commission that that investigated the 2001 terror attacks. Two of the attacks’ perpetrators were found to have overstayed their visas.

The U.S. issued more than 10 million non-immigrant visas from October 2014 through September of 2015.

Visitors who overstay their visas are investigated to determine whether they have applied for immigration benefits, left the country or pose a security risk.

Homeland Security officials agreed with the report’s findings.