Brutus was originally one out of two convicts who were both charged for 5 crimes (21 counts of armed murder, 29 counts of assault (17 aggrevated and 12 sexual), 3 bombings and one instance of eating a little boy's puppy) before being killed on the electric chair six months to the events of the game and then "tinkered with" by Clement Darling. The two shared the same mutant appearance; big and fat, covered in tattoos, wearing a black skin-tight mask on their heads (very similar to that of the second game's boss Strength), and with a multi-dagger crossbow-like launcher on their handless right arms. Clement originally sent them both to attack G and Isaac Washington; however, his partner moved in to attack Brutus instead. Brutus responded by elbowing his partner in the face, breaking his neck, and beating him into a bloody pulp. He then lets out a massive roar, as well as a dagger, as he turns his attention to the two agents.
Brutus must have been an inmate tested on for experimentation. His right hand is replaced with a mechanized weapon that similarly fires bolts like from crossbows of his own extension and it will be known in the last phase of the first attack. It is unclear why his weaponized hand is his weak point until in the Extended Cut, the battery pack keeping him alive was also a weak point.
Brutus' main form of attack is to shoot the crossbow bolts from his arm at the player(s). These must be shot to avoid damage and with more Health. Unlike other projectiles, they don't always move in a straight path and are easiest to stop when initially fired. At the same time, his weakpoint is the same "hand" firing the bolts.
At certain points during the battle, you must also fight a small group of shielded police-like mutants who can be difficult to hit. If a grenade is available, throwing it is the easiest way to dispense of these monsters.
In the Extended Cut, instead of shielded mutants, he summons inmates and cops.