Lowry rarely spoke due to his lisp. He was a vicious man with little in the way of humanity.
Byers used Lowry to get into the medical wing to see Pfeiffer by picking a fight with Lowry by mocking his lisp. Lowry waited until the guards had left to really beat the crap out of Byers in the yard.
Later, Jeremy Wash, the man who used Pfeiffer as a hitman and Pfeiffer's attorney, asked Lowry to kill Pfeiffer.
He failed in his attempt on Douglas Pfeiffer's life when Byers hit Lowry over the head with a bedpan.