The former scouting director of the St. Louis Cardinals pleaded guilty Friday to criminal charges in connection with an unauthorized breach of the Houston Astros computer network. It was the first known case of cyber-espionage involving a professional sports team hacking into another team’s database.

The Cardinals fired Chris Correa, 35, last summer, weeks after news broke that the Federal Bureau of Investigation was probing whether Cardinals employees illegally accessed the Astros’ private database of player information. Major League Baseball had asked the FBI to look into the matter after information related to potential player trades was released anonymously online in 2014.

Appearing in Houston federal court, Mr. Correa pled guilty to five counts of unauthorized access to computer information. Each count carries a maximum possible sentence of five years in prison and a $250,000 fine.

Mr. Correa worked previously under Astros general manager Jeff Luhnow in St. Louis before Mr. Luhnow left for the top baseball-operations job in Houston in late 2011. Before being promoted to scouting director in late 2014, Mr. Correa previously was the Cardinals’ manager of baseball development, the department responsible for statistical analysis.

According to a statement of charges filed by the U.S. attorney’s office, Mr. Correa accessed the Astros’ computer network repeatedly in 2013 and 2014. In March 2013, he downloaded an Excel file containing a list of every player eligible for that year’s amateur draft and how each Astros scout ranked them. In June, on the morning of the third day of the draft, Mr. Correa again viewed the Astros’ internal draft page, filtering results to view only players who had to be selected.