DNA evidence has linked the death of Casey Mahoney, whose body was found last week, to two earlier homicides at the hands of the so-called Kensington strangler.
With the third confirmed victim, police say the suspect now fits the classification of a serial killer.
Mayor Nutter also announced today that a $30,000 reward has been posted for information leading to the arrest and conviction of the man responsible for the killings.
"We are serious about getting this psycho off the streets," Nutter said at a news conference in Kensington. "We will not tolerate this insanity."
The first victim, 21-year-old Elaine Goldberg, was found in a lot on Nov. 3. The second victim, 35-year-old Nicole Piacentini, was found at an abandoned building on Nov. 13.
Mahoney, 27, was found on Dec. 15 in the woods above the railroad tracks that run along East Tusculum Street.
All three victims had struggled with addiction and appeared to be deeply engaged in the neighborhood's dangerous drug subculture.
The victims all had been sexually assaulted and strangled.