Doctors confirmed that Redskins linebacker Reuben Foster tore his ACL in Monday's OTA practice.(Toni L. Sandys/The Washington Post)

Redskins linebacker Reuben Foster tore his ACL and will miss the coming season, a person with knowledge of the situation confirmed Tuesday night. The team initially feared Foster had torn his ACL in a freak fall during Monday’s offseason practice but was waiting for him to see a specialist Tuesday for confirmation of a diagnosis.

Doctors worry that Foster might have nerve damage as well, but they won’t know until he has surgery. It is expected he will have surgery once the swelling in the knee goes down.

Foster injured his left knee Monday on his first play as a Redskin, accidentally stepping on a teammate’s foot and falling awkwardly in the initial drill of the team’s first practice. The team had hoped he would be a dominant piece of an aggressive young defense, penciling him in as a starter at middle linebacker.

He joined the Redskins three days after the San Francisco 49ers released him in November, the day after his second domestic violence arrest. In that incident, his girlfriend told Tampa police that he hit her during an argument at the team’s hotel the night before a game against the Tampa Bay Buccaneers. Washington was the only team to claim him, and he was placed on the Commissioner Exempt List while the league investigated the incident.

The Tampa charges were dropped in January, and the Redskins went into this offseason with the expectation that Foster would be a key part of the team’s defense .

In a statement released last month, the NFL said it did not find any evidence that Foster violated the league’s personal conduct policy during the Tampa incident.

He was suspended for the first two games last year, while a member of the 49ers, following his first domestic violence arrest and a weapons charge in California, as well as an arrest for marijuana possession in Tuscaloosa, Ala. The domestic violence charges were later dropped, the weapons charge was reduced from a felony to misdemeanor and the marijuana charge was dropped when he entered a diversion program for first-time offenders. When the league suspended him last year, it said the punishment was for the weapons and drug offenses.

Foster’s two-year NFL career has been a mix of on-field promise and off-field trouble. When healthy and not suspended, Foster has shown glimpses of being one of the league’s most dominant interior linebackers, with the ability to deliver big tackles and defend passes in the middle of the field. Despite battling ankle injuries his rookie season in San Francisco, Foster had 72 total tackles in 10 games. Last season he had another 25 tackles in his six starts before his release.

“I don’t know how to process it, really,” Redskins Coach Jay Gruden said after Monday’s OTA. “We’ve had some bad luck over here for the last couple years. This one here takes the cake because this was a non-contact drill and there was really no contact involved in it. He just landed funny. But we have to move on. We have to get the guys ready that are here and we have to do the best we can to get Reuben healthy again and move on.”

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