LOS ANGELES (AP) — U.S. immigration agents waste their time logging in and out of archaic computer systems while trying to track down foreigners suspected of overstaying their visas only to find out later that many visa holders have left the country, said a government watchdog report released Thursday.

Agents and analysts must use 10 to 40 passwords to access the computer systems and 40 percent of the cases investigated one year turned out not to be overstays, said the report by the U.S. Department of Homeland Security's Office of Inspector General.

The report also disclosed that U.S. Immigrat...