This is not a surprise. As enforcement efforts increase, smugglers will naturally turn to corrupting enforcement officers as a way to do business.

Note that this isn’t all just that though:

When the Homeland Security Department was created in 2003, the internal affairs unit was dissolved and its functions spread among other agencies. Since the unit was reborn last year, it has grown from five investigators to a projected 200 by the end of the year.

Once again Bush and His Evil Minions^™ manage to completely f^%$ up the execution.

Note that the best way to reduce corruption is to make sure that the border guards are well paid and have good working conditions. Underpaid and abused employees are more receptive to graft.