There are plenty of good old Americans who do this type of disgusting, evil sh_t. Jeffrey Dahmer, John Wayne Gacy, Phillip Garrido (who abducted Jaycee Dugard), Ken Parnell (who kidnapped and sexually abused Steven Stayner for years), Cameron Hooker (who kidnapped and sexually abused Colleen Stan for 7 years). The list goes on and on. While these sick monsters need to be put down (or better yet, allowed to live tied up like these girls for the rest of their lives), its not an immigration issue.
But they all seemed like such nice people!
Sure there are. But it is rare that three siblings like this do something like this on such a scale. Deeper research will reveal deeply seeded feelings of hatred for America/Americans because of perceived racism and fellings of inadequacy, blaming it on the racist system over their own shortcomings.