(CNN) -- Fears of a serial killer stalking women in Philadelphia, Pennsylvania, have prompted some residents to take matters into their own hands -- and onto the internet, with frightful results for one man.

Many residents of the city have joined a Facebook page titled "Catch the Kensington Strangler, before he catches someone you love," and police say a male Philadelphia resident was falsely accused of being responsible for three strangulation murders and three other assaults that have occurred in the central Philadelphia area in recent weeks.

The post contained a photograph of the man and listed his address and contact information, police spokesman Lt. Ray Evers told CNN.

Shortly after the posting, a group of people began gathering outside the man's home, prompting him to call the police, according to Evers.

"He probably feared for his life." Evers said.

Police later escorted the man to the city's special victims unit, where he was interviewed and his DNA was compared with samples taken from the scene of the three killings that all came from the same individual.

The man's DNA didn't match the DNA from the crime scenes, and he was cleared.

Police said they are unsure who made the accusation, but they believe whoever did it had a vendetta against the man and could face charges if caught.

Authorities are warning female residents not to walk alone, as police and community watch groups continue to search for the killer.

"The task force we've put together is sweeping the area, but we caution females in the area not go it alone at any cost," Evers said.

On Tuesday night, police announced they are looking for a serial killer after it was determined that DNA found at the scene of the third homicide matched that found at two previous killings.

The partially clothed body of the third victim, Casey Mahoney, 27, was discovered December 15, according to police spokeswoman Jillian Russell. Mahoney had been sexually assaulted and strangled.

Two other women, Elaine Goldberg, 21, and Nicole Piacentini, 35, were killed in November.

Police originally told CNN that all of the homicide victims were involved in prostitution and narcotics, but a Philadelphia TV station, WCAU-TV, has reported that Goldberg was a nursing student who attended Gwynedd-Mercy College.

Authorities are offering a $30,000 reward for information leading to an arrest and conviction, said task force Capt. James Clark. Earlier this week, authorities said they believe the attacker likely is still within a 10-block radius of where the attacks occurred.

Police said the assault victims described the attacker as an African-American male in his early 20s, weighing between 160 and 170 pounds.

Authorities say they lack DNA evidence that would link the three assaults, in which the victims were choked in a manner similar to the homicide victims. Too much time had elapsed between the initial two assaults in October and the victims' notifying police.

"The assault victims did not come forward until police began combing the Kensington (neighborhood) for suspects and potential victims following the November homicides," Evers said.

Federal agents joined the investigation earlier this month, bringing in resources from the FBI's behavioral analysis unit, violent criminal apprehension program, and the National Center for the Analysis of Violent Crime.

"The investigation appears to be limited to Philadelphia," FBI spokesman J.J. Klaver said this week. "This could change if there are any indications that the subject or subjects responsible for the crimes ... are linked to similar crimes elsewhere."

Police have said the assault victims described the attacker as an African-American male in his early 20s, weighing between 160 and 170 pounds.

Police said a third assault victim was pulled into an alley earlier this month. Despite being choked, punched and hit on the head with a brick, the 33-year-old woman escaped, and her assailant fled the scene, according to a police report.