Those charged with reuniting families and locating missing children in the wake of Hurricane Katrina say it may take “months and months” to resolve the thousands of missing-person reports, and more cases are expected as Hurricane Rita roars ashore.

“It gets more difficult every day,” said David Mesinar, a retired Las Vegas police detective who is among the 40 or so volunteers – some working up to 14 hours per day – with the National Center for Missing and Exploited Children.

“We are just so overwhelmed,” Mesinar, 59, said, taking stock of a frustrating day on the ground along the Mississippi coast. “It’s so disappointing to not be able to solve so many of these cases.”

Three weeks after Katrina hit the Gulf Coast, the number of cases has continued to rise.

As of noon Friday, a special hot line set up at the national center’s Alexandria, Va., headquarters had fielded 16,275 calls from those looking for information on missing children or family members. In Louisiana alone, the center has opened 3,783 cases of missing children or children looking for their parents – an increase of 788 cases since the beginning of the week.

Combined with calls to its permanent hot line, the center has taken more than 25,000 calls. This week alone, 3,752 calls have come in.

“Parents are just now getting organized enough to get to a phone or some means of communication,” said Ben Ermini, executive director of case management operations for the center.

More than a dozen volunteers have been deployed to states affected by Katrina. The week before the hurricane hit, Canon donated 200 digital cameras. Volunteers use them to take pictures and update rolls at shelters across the region.

Those photos are also put on various Web sites so families can search for loved ones via computers.

Four days after the storm, the Justice Department asked the center to begin a hot line specifically for families separated by the hurricane. Within three days, 35 volunteers in Alexandria began answering the first phone calls to report missing children.

“They canceled vacations, they ended their long weekends,” said Bob Snow, who manages the day shift at the call center. “We’ve had no shortage of people to help us out.”