What stands out about the strangler, if it is Rodriguez, is that he crossed racial lines in choosing his victims.
"If in fact the person arrested is the killer, it would be unusual to have serial killings across racial lines," Fox said. "Most white killers kill white victims and black killers kill black victims."
None of the victims murdered were African American, like Rodriguez.
"Serial killers are motivated by sexual fantasy and sadism and have a particular type that they're attracted...It's a crime of selection and killers will pick and choose," Fox said.
Sources have described Rodriguez as a mild-mannered, quiet guy who didn't stand out.
Forensic psychologists said that serial killers often fly under the radar.
"They don't look and act like our stereotype of a serial killer...If someone looked and acted bizarre, if someone looked like Jason from 'Friday the Thirteenth,' we'd avoid them. Part of the way a serial killer operates is they look so extraordinarily ordinary," Fox said.
"This is not about being stark raving mad," said Dr. N.G. Berrill, director of New York Center for Neuropsychology and Forensic Behavioral Science. "This is not being a lunatic. This about cultivating this sadistic and predatory instinct. If you're not a victim, you don't know about it."
One of the things that helped catch the alleged suspect is that he may have left some victims alive, forensic psychologists said.
In early October, a 30-year-old woman was choked to the point of unconsciousness in the same spot where one of the victim's bodies was found.
She came to the police after the murder of the first victim in November. She helped police generate a sketch of the man believed to be Rodriguez.
"There's three other assaults in the area that kind of fit the pattern of the homicide and the results of that are still pending," Lt. Ray Evers from the Philadelphia Police Department said. "At this time, they're still open investigations."
Police sources told WPVI that two of those victims have positively identified Rodriguez from his mug shot.
Some of the alleged victims had previously described the "Kensington Strangler" as having a quiet voice and referring to himself as "Anthony."
Rodriguez grew up blocks from the Kensington neighborhood that became the scene of the strangling deaths of the women. All of the women's bodies were found in a 10 block radius of one another.
The African American man was adopted by a Spanish-speaking family as a child, the Philadelphia Inquirer reported. He had no arrests as a minor, but turned to drugs as he entered adulthood.
Rodriguez spent time in jail in the summer of 2010 before being convicted in October 2010 on felony drug charges. He was sentenced to one year of probation just weeks before the murder of Eileen Goldberg on Nov. 3, 2010.
Eileen Goldberg's father, Joe Goldberg, is relieved that the "Kensington Strangler" may have been caught.
"I was happy to see him arrested," Goldberg said. "I was pleased to see him off the street because...it was intolerable on a daily basis that the guy who killed my daughter is out free as a bird and quite possibly getting ready to kill his next victim."
Goldberg called Rodriguez's statement to investigators that he didn't mean to kill the women "idiotic."
"I don't buy that. To choke the life out of somebody, you've got to be squeezing their neck for a considerable amount of time. If it's something that you didn't want to do, there was plenty of time not to do it," Goldberg said.
Eileen Goldberg, a 21-year-old nursing student, had struggled with prescription drug addiction, but had recently celebrated 30 days of sobriety before her murder.
"She was preaching the gospel of recovery," Goldberg said. "He snatched her life away before she ever had a chance to get married, have a baby, become what she wanted to be."
The Associated Press contributed to this report.