CLEVELAND >> Major League Baseball concluded the Houston Astros were not trying to steal signs when they had an employee monitor opposing dugouts during the postseason.

The Cleveland Indians filed a complaint following Game 3 of the AL Division Series after the employee was observed aiming his cellphone into their dugout and taking pictures or video. Two people familiar with the situation said the Astros tried to get a second person next to the dugout after the employee was removed by security. The people spoke to the Associated Press on condition of anonymity because of the sensitivity of the matter.

The same employee was removed from an area near Boston’s dugout before Game 1 of the ALCS.

Today, MLB issued a statement saying its department of investigations determined “that an Astros employee was monitoring the field to ensure that the opposing club was not violating any rules.”

MLB has told all clubs still in the playoffs “to refrain from these types of efforts.”

Prior to the postseason, MLB said “a number of clubs” called Commissioner Rob Manfred to express concerns about video equipment being used to steal signs. To address those worries, the commissioner instituted a new prohibition on the use of certain in-stadium cameras, beefing up MLB security at games and monitoring video rooms.

The investigation had threatened to tarnish this postseason and had cast aspersions on the defending World Series champion Astros.

General manager Jeff Luhnow said the Astros have been proactive in policing other ballparks for “suspicious activity” and the team has uncovered some “multiple” times. Luhnow said the club will abide by MLB’s guidelines and that any prior monitoring was done as protection.

“We were playing defense, we were not playing offense,” Luhnow said before Game 4 of the ALCS.

Stealing signs has been part of baseball since the invention of the game. Teams routinely try to gain an advantage by trying to detect patterns, whether it’s a catcher showing signs to a pitcher on the mound or a third-base coach relaying signs to a batter.

However, new technology may have given teams an unfair advantage as the use of high-definition, high-speed cameras allows teams to peer where they couldn’t before.

“There’s some unintended consequences that come with the advancement of technology,” Astros manager A.J. Hinch said. “It’s a league-wide conversation that needs to happen in time. It’s happening right now during a really important series and I just think it’s bigger than us. It’s bigger than any team. It’s bigger than any series. It needs to be corralled because of the state of the concern over it.

“The competitive edges nowadays are so narrow. You’re trying to find everything you can. And whether that’s pitch tipping, pitch sequencing, changing your signs, changing your location of your defenders — this is a bigger topic that’s going to take a lot more time than an overnight story and concern and people’s curiosities.”

The Indians had been upset when an unidentified man, who had been issued a credential before the Oct. 8 game in Cleveland, appeared to be trying to view scouting reports in the team’s dugout on Houston’s players, one person told AP.

The Red Sox had been warned before their series-opening game to look out for the man, the AP was told by the people.

During the early innings in Game 3, the Indians became aware that the man standing near their dugout in Progressive Field was aiming his cellphone into their dugout. He stood out because he was wearing a suit jacket in a restricted area reserved for photographers, a member of the team’s social media department and where TV reporters are permitted to stand, one of the sources said.

After being approached by security, the man left without incident but a second person attempted to replace him several innings later and was denied access to the field area, the AP was told.

The Indians entered the series concerned the Astros, who have been suspected of cheating in the past, had stolen some signs or had other useful information about them, one person said.

Following Game 3, Indians starter Mike Clevinger alluded to the Astros having an advantage. Clevinger allowed one run and three hits in five innings, but took the loss as the Indians were pounded 11-3.

“A lot of stuff. A lot of things,” Clevinger said when asked what happened. “I’m going to keep it really short. We were a little bit, I don’t know, kind of had our backs against the wall before this started when it came to the analytical side. But everybody was out there giving it their all, they just had some really good arms to back it up.”

The Red Sox were fined last season by MLB for using an Apple Watch to try to steal signs from the rival New York Yankees.

There have been previous suspicions about the Astros.

Indians pitcher Trevor Bauer went on Twitter earlier this season and intimated that Houston’s pitchers were possibly using pine tar to improve the rate of spin on pitches. Bauer wasn’t specific, but Astros pitchers Lance McCullers Jr. and Collin McHugh defended themselves on social media.

Yahoo reported Oakland’s players believed Astros players were relaying stolen signs during games and the team asked for an investigation.