"We've talked numerous times over the last couple of weeks and Martin has concluded that this is the end of the line for him. He didn't feel like himself during the Montiel fight and is happy with what  he has accomplished in the sport. As he put it 'I owe everything to boxing and I don't want to fight anymore if I can't go at a world class level.' "  

"The fans have always been very supportive of Martin and he wants to thank them for all their years of terrific support, it's meant so much to him. Bob Arum and the whole Top Rank family have been great to work with and he also wishes to thank them for the opportunities they gave him, said Espinoza.   

Castillo was stopped by Fernando Montiel in the fourth round on February 16, 2008 in a super flyweight title bout in which Montiel was defending his World Boxing Organization belt.  

The 31 year old Castillo, a native of Mexico City, finishes his career with a record of 33-2 with seventeen knockouts. He won the WBA super flyweight by defeating Alexander Munoz on December 3, 2004 in Laredo, Texas.  

Long a popular fan favorite with boxing fans in the United States, Castillo also fought three times in Japan, his only loss there coming when his war with Nobuo Nashiro was stopped on cuts in the tenth round. Prior to that stoppage loss, Castillo had defended his title three times including a rematch with Munoz and a win over 1996 US Olympian Eric Morel.  

Castillo made his pro debut on July 27, 1998 after an outstanding amateur career that featured his participating in the 1996 Olympics representing Mexico. He also defeated Floyd Mayweather Jr. in the amateur ranks.