How about, "the bribes to La Migra agents have increased to the point where more illegals (and the drugs they carry) are allowed to cross."
Fact is there is very little corruption on the border, when it comes to illegal aliens. That stuff happens inside the US, at the offices where the documents are issued.
As for drugs, the INS has the same 10% of idiots that every agency has, but those idiots are moving drugs, not illegals.