Video shows Boston bombing suspects at the gym three days before attacks

A video shows the Boston Marathon bombing suspects working out at a gym only days before the attacks.

According to CNN, the video captures Tamerlan and Dzhokhar Tsarnaev at Wai Kru, a mixed martial arts center, with a friend on Friday, April 12, at 2:45 p.m. The bombing took place the following Monday.

The video shows the manager asking the two when they arrive to remove their shoes as gym rules dictate. Dzhokhar, 19, takes off his shoes. Tamerlan, 26, refuses to do so and gets in an argument.

Later, the manager told CNN, the argument prompted him to email the owner of the gym asking to ban Tamerlan and saying, "He's arrogant, selfish and never helps anyone else."

The two proceed to work out, jumping rope. Tamerlan worked out at the gym a couple of times per month for free as a professional courtesy due to his being a nationally ranked Golden Gloves boxer, according to the gym manager. His skills with the rope are evident.

Dzhokhar, who rarely used the gym, appears to pause often as he exercises. The gym manager told CNN he remembered seeing Dzhokhar "two or three times" in roughly two years.