The former head of Wal-Mart's Mexico operations is stepping down from his current board positions at MetLife, effective immediately.

The insurance giant announced Tuesday afternoon that Eduardo Castro-Wright had resigned "due to personal reasons."

Castro-Wright was leading Wal-Mart de Mexico at the time of an alleged widespread bribery scheme there. The New York Times reported last weekend that Castro-Wright was the driving force behind millions of dollars in alleged bribes given to Mexican officials in exchange for speedier building permits and other favors to help it expand aggressively in the region.

Experts say Castro-Wright could face federal criminal charges.

On Tuesday, MetLife filed a letter with the Securities and Exchange Commission from Castro-Wright and addressed to MetLife CEO and Chairman Steven Kandarian.

"Over the past weekend, I notified you of recent events that will require my immediate and personal attention. As a result, I will be stepping down from the board," Castro-Wright wrote. "I now must focus my energy in spending personal time with my family and in protecting my good name and business reputation."

Castro-Wright will step down from two board positions: one with holding company MetLife Inc. and another with Metropolitan Life Insurance Co. The New York company said Castro-Wright was first elected to its boards in March 2008.

Last fall, Wal-Mart announced that Castro-Wright would retire July 1 from his current role as vice chairman of Wal-Mart and CEO of its global ecommerce and global sourcing business.

Castro-Wright joined Wal-Mart in 2001 and led its business in Mexico until becoming president and CEO of its U.S. operations in 2005. In June 2010, Wal-Mart appointed Bill Simon, who had been chief operating officer, to take over its U.S. operations, shifting Castro-Wright to lead to the retailer's online and sourcing operations.