(NBC Sports) - Michael S. Schmidt of the New York Times reports that, after an investigation, Major League Baseball has determined that the Red Sox illegally used an Apple Watch to steal signs from the Yankees.

The Red Sox hosted the Yankees in mid-August for a three-game set, winning two of the three games. Yankees GM Brian Cashman filed a complaint to the commissioner’s office using video of the Red Sox dugout which showed a trainer looking at his Apple Watch, then relaying a message to players. Presumably, this information allowed the hitters to know what pitch was coming.

When confronted by the commissioner’s office, the Red Sox admitted that trainers had been receiving signals from video replay personnel, which was then relayed to the players. It’s not known how long the Red Sox have been at it, but it’s been “at least several weeks,” according to Schmidt. The Red Sox contend that manager John Farrell, GM Dave Dombrowski, and other front office personnel were not aware of the operation.

In a bit of gamesmanship, the Red Sox filed a complaint of their own to the commissioner’s office, alleging that the Yankees use a YES Network camera exclusively to steal signs. The Red Sox also accused the Indians of stealing signs after Game 1 of the ALDS last year.

Stealing signs is not forbidden by the rulebook, but using technology to do so is. So the Red Sox are clearly at fault here and will likely face some sort of punishment. Schmidt did not speculate as to what that could be.

The Red Sox, who recently lost three of four games to the Yankees in New York, have a narrow 2.5-game lead over their rival in the AL East standings.