WASHINGTON — Front-office personnel for the St. Louis Cardinals, one of the most successful teams in baseball over the past two decades, are under investigation by the F.B.I. and Justice Department prosecutors, accused of hacking into an internal network of the Houston Astros to steal closely guarded information about players.

Investigators have uncovered evidence that Cardinals employees broke into a network of the Astros that housed special databases the team had built, law enforcement officials said. Internal discussions about trades, proprietary statistics and scouting reports were compromised, said the officials, who were not authorized to discuss a continuing investigation.

The officials did not say which employees were the focus of the investigation or whether the team’s highest-ranking officials were aware of the hacking or authorized it. The investigation is being led by the F.B.I.’s Houston field office and has progressed to the point that subpoenas have been served on the Cardinals and Major League Baseball for electronic correspondence.

Law enforcement officials believe the hacking was executed by vengeful front-office employees for the Cardinals hoping to wreak havoc on the work of Jeff Luhnow, the Astros’ general manager, who had been a successful and polarizing executive with the Cardinals until 2011.