Congressman Eric Swalwell is dealing with a growing pile of legal headaches ... he's now being investigated by the Department of Homeland Security. New complaints allege Swalwell employed a Brazilian nanny whose work authorization may have expired, according to KTLA . What's more ... the gubernatorial candidate allegedly didn't exactly follow the rulebook when it came to paying her. The au-pair, Amanda Raissa Barbosa , allegedly stayed on the job while getting paid in a way that may have