PHILADELPHIA — A serial killer who police say sexually assaulted and strangled three women, and possibly attacked three others, in a neighborhood rife with drugs and prostitution might want to hope that authorities find him before the neighbors do.

Residents of Kensington, who once severely beat a suspected rapist based on a police photo, have posted hundreds of comments and theories about the case on a Facebook page titled "Catch the Kensington Strangler, before he catches someone you love."

One post that falsely identified a suspect led to an angry crowd outside the man's home. Fearing vigilantes, he called police — who later cleared him, and then scolded residents.

"We will not tolerate anyone taking vigilante action," Police Commissioner Charles Ramsey warned. "If you see someone suspicious, call 911. We will get there. We will handle."

Police on Tuesday linked a third slaying to a predator who they say raped, beat and strangled two women over the past few weeks. Three other women have reported being sexually assaulted; two of them said they were choked into unconsciousness.

So far, police only have a composite sketch and grainy surveillance photo of a possible suspect; $37,000 in reward money is being offered.

Once a middle-class neighborhood of rowhomes a few miles northeast of downtown, Kensington has become a high-crime area with a culture of open-air drugs and prostitution. But it also boasts a nascent gentrification effort as young homeowners and artists move in, attracted by the affordable prices.

Lifelong resident Edward Neisser, 62, angrily blamed the neighborhood's ills on too many halfway houses and abandoned, overgrown properties.

"It's a disgrace what's going on around here," Neisser said. "The city could turn around and clean up these lots so none of this stuff happens."

But Jayme Guokas, a relative newcomer, said he was unwilling to write off the neighborhood where he has spent the past six years.

"It's one person who's doing these things," Guokas, a 35-year-old carpenter, said of the strangler. "That's counteracted by a lot of working people who are trying to invest in the neighborhood and make it better."

Guokas lives a few doors down from where police found the body of 35-year-old Nicole Piacentini of Philadelphia on Nov. 13. Twenty-one-year-old Elaine Goldberg of Philadelphia had met the same fate 10 days earlier; the body of Casey Mahoney, 27, of East Stroudsburg, was found Dec. 15.

The women, all of whom have been described as struggling with drug addiction, were found within 10 blocks of each other.

And yet even with the murders, police said drug sales and prostitution continue unabated.

"It is somewhat disturbing that, in light of all this information, all of this warning, that women and men are still frequenting this area and engaging in high-risk behavior," Deputy Commissioner William Blackburn said.

Authorities have arrested 120 people involved in prostitution in Kensington since Nov. 19 and obtained DNA swabs from many of them, Blackburn said. More than 40 have been cleared, and tests are pending on the rest.

Police stressed that neighbors who see something suspicious should call 911 and not take matters into their own hands. In another Kensington case last year, a man suspected of raping an 11-year-old girl was severely beaten by angry neighbors who recognized him from a police photo. He was later charged and pleaded guilty.

Mayor Michael Nutter, speaking on Tuesday just steps from where Piacentini's body was found, pleaded for information from residents who might be keeping quiet out of fear or loyalty.

He offered $30,000 for information that leads to the arrest and conviction of the perpetrator. Separately, the local Fraternal Order of Police and Councilman Frank DiCicco have offered $7,000 for help simply leading to an arrest with a DNA match.

"We strongly believe that someone — possibly in the neighborhood — someone, somewhere in the city of Philadelphia knows who this person is, or knows about them," Nutter said. "We are serious about getting this psycho off the streets."

Associated Press writer Maryclaire Dale contributed to this report.