A serial rapist in Frankford?

Police are worried that an armed sexual predator might be on the loose in the city's Frankford section - based on similarities in three nighttime assaults on young women that have occurred since June within a five-block radius.

Chief Inspector William Colarulo of the Philadelphia police special-investigations unit said the department was prompted to warn the public yesterday because two of the incidents - in which the suspect allegedly pulled a small silver revolver on his victims before assaulting them - took place this week.

"You can see we have some similarities - we also have some differences - but we do believe that it's important because these happened within the same five blocks," Colarulo said at a news conference.

Police also released a composite sketch based on the most recent assault, which took place around 10 p.m. Thursday on a 16-year-old girl who was walking alone after exiting the Market-Frankford El at the Margaret and Orthodox station.

The alleged rapist is described by police as a 6-foot-tall black male, about 170-180 pounds, medium build, around 18 years old, wearing a gray hooded sweatshirt with a red emblem on the front and dark denim pants.

In that episode, according to police, the attacker placed a silver handgun to the girl's head and demanded money before raping her in an alleyway on Darrah Street near Foulkrod.

Another possibly related incident took place at 6 a.m. on Tuesday involving a 21-year-old woman walking to her car on Wake-ling Street near Darrah. Colarulo said that the attacker pointed a revolver at the victim, then robbed and sexually assaulted her.

Police are also looking at another unsolved sexual-assault case in Frankford on June 11, in which a young male with a similar description held a knife to the throat of a 16-year-old girl in an alley behind a CVS store on Adams Avenue near Unity, demanded money and then assaulted her.

Colarulo said that police have fingerprint evidence from one of the attacks and possible DNA evidence from two of them, and that the processing of those results has been accelerated.

He issued one other warning, noting that because the women were walking alone at night or early in the morning, "they were easy prey for this individual." *