Use a question survey or use extermination?
The survey is initial step. The government needs to have them standby while they verify. If they get past that check, then if they are ever found to have lied, then they get immediately arrested and deported. Will someone lie to get it? Yes, quite likely, but we have to trust the government to figure that out. If they cannot, then, block all immigrants and visitors overall. Let in only those that have been truly vetted. Heck, we do not need more immigrants, so close the border. Hey, that fixes it.