Philadelphia police said the 71-year-old father of the Angels' Reggie Jackson was robbed at knifepoint in his fur store.
Among the items stolen was a Cartier watch bearing the New York Yankees' emblem commemorating Jackson's 400th major league home run, police said.
Martinez Jackson, who was not harmed in the incident, told the Philadelphia Inquirer he was held up by two men who had been in his store twice before posing as shoppers. One man pulled a knife and demanded a $1,000 raccoon coat.
The robbers fled when a customer entered the store.