Barely three days before the Boston Marathon Bombings, the alleged bombers worked out at Wai Kru, a mixed martial arts gym, according to new video.

The security footage from the gym shows Tamerlan and Dzhokhar Tsarnaev on the afternoon of April 12. At around 3 p.m. the two brothers were jumping rope and stretching in one of the rings at the gym. The video, first aired by CNN, gives hints about the lead up to the April 15 attacks.

The video can be seen here.

The gym manager, only identified as Michael, told CNN that Tamerlan shaved his beard shortly before the attacks.

"Shaving the beard may be a way to blend in, not to attract scrutiny from security services in carrying out the Boston attacks," said CNN terror analyst Paul Cruickshank.

It was reported that Tamerlan visited the gym several times a month and the manager also pointed out another Chechen from the gym to the FBI. Ibragim Todashev was under investigation by the FBI in connection to a triple murder from 2011. However, Todashev was recently killed in a confrontation with an FBI agent, according to CNN.

While Tamerlan was at the gym on April 12 he is reported to have had a confrontation with the manager. When asked to remove his shoes upon entering the facility, Tamerlan gets into an argument. The manager later sent an email to the gym owner, asking that Tamerlan be band from the facility, according to CNN.

The owner of the gym, John Allan claimed that he and the facility were cooperating with the FBI and Homeland Joint Task Force, according to the New York Daily News.

Tamerlan died in a shootout with police. His younger brother remains in custody.